An engine system may include an engine including a plurality of intake lines through which outside air supplied to combustion chamber flows, a first electric supercharger and a second electric supercharger disposed respectively in the plurality of intake lines, a first exhaust gas recirculation (EGR) device including a first EGR line branched from an exhaust manifold and joining an intake manifold and a first EGR valve disposed in the first EGR line, and a controller determining an engine target torque according to a driving condition of the engine, setting an engine torque within an operation region of the first EGR device when the engine target torque is in a torque dead band between the operation region of the first EGR device and a non-operation region thereof, and compensating a difference value between the engine target torque and the engine torque by a hybrid electric vehicle (HEV) motor.

An EGR device includes an EGR flow path, an EGR valve, a stepping motor, a motor driver, a return spring, a speed detector, and an opening degree estimator. The EGR flow path conveys exhaust gas from an exhaust flow path of an engine to an intake flow path. The EGR valve is disposed on the EGR flow path. The stepping motor drives the EGR valve to open to close. The motor driver supplies driving power to the stepping motor. The return spring urges the EGR valve in a valve closing direction. The speed detector detects an output shaft rotation speed of the engine. The opening degree estimator estimates an opening degree of the EGR valve. The motor driver changes a drive frequency of the stepping motor according to variations of the output shaft rotation speed detected by the speed detector and the opening degree estimated by the opening degree estimator.

The present disclosure belongs to the technical field of engines, and specifically relates to a gas mixing device and a natural gas engine. The gas mixing device includes a housing, a first mixing core, a first measurement assembly, a second mixing core, and a second measurement assembly. An air inlet and a combustion gas inlet respectively communicate with the first mixing core to form a mixed gas in the first mixing core; the first measurement assembly is connected to the first mixing core, the second mixing core is connected in the housing, the EGR exhaust gas inlet and the first mixing core respectively communicate with the second mixing core, and the second measurement assembly is connected to the EGR exhaust gas inlet. In the gas mixing device according to the embodiment of the present disclosure, the first measurement assembly and the second measurement assembly respectively provide measurement data for obtaining flow rates of the air, combustion gas and EGR exhaust gas. As compared with the speed-density method and the throttle model, the results tend to be more accurate, which facilitates a control of the air-fuel ratio to improve the conversion efficiency of the three-way catalytic converter.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

This EGR system is applied to a vehicle including an exhaust purification device capable of purifying NOx, and is provided with: an EGR passageway; a flow volume modification mechanism; and a control device which, when the NOx concentration in exhaust discharged from the exhaust purification device is greater than a reference value, starts to perform a control process for controlling the flow volume modification mechanism so that the ratio of the flow volume of a first exhaust that flows into a tail pipe decreases and the ratio of the flow volume of a second exhaust that flows into the EGR passageway increases, and makes the ratio of the flow volume of the second exhaust greater than the ratio of the flow volume of the first exhaust during the control process.

This EGR system is applied to a vehicle including an exhaust purification device capable of purifying NOx, and is provided with: an EGR passageway; a flow volume modification mechanism; and a control device which, when the NOx concentration in exhaust discharged from the exhaust purification device is greater than a reference value, starts to perform a control process for controlling the flow volume modification mechanism so that the ratio of the flow volume of a first exhaust that flows into a tail pipe decreases and the ratio of the flow volume of a second exhaust that flows into the EGR passageway increases, and makes the ratio of the flow volume of the second exhaust greater than the ratio of the flow volume of the first exhaust during the control process.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

In some embodiments the disclosure is directed to a closed-loop piston engine system using a recirculating carbon dioxide (CO.sub.2) system with supercritical carbon dioxide (scCO.sub.2) as a working fluid. The closed-loop piston engine system may include a scCO.sub.2 injector; a superheating nozzle region; a first valve; a second valve; a piston moving in the cylinder and coupled with a crankshaft, the piston being driven toward a centerline of the crankshaft during a power stroke using a connecting rod and causing the crankshaft to rotate thereby causing one power stroke per piston per crankshaft rotation and thereby producing two power strokes for every single power stroke that a similar engine would produce if run as a hydrocarbon fuel powered internal combustion engine. The recirculating CO.sub.2 system recirculates the used carbon dioxide and there are no carbon dioxide emissions from the system.

An engine system includes: an internal combustion engine having a plurality of cylinders; a bypass valve arranged to receive exhaust output from at least a dedicated one of the cylinders and to selectively one of: direct the exhaust through an exhaust system to atmosphere; and direct the exhaust to an exhaust gas recirculation (EGR) valve; the EGR valve, where the EGR valve is configured to, when open, enable flow of the exhaust to an intake manifold of the internal combustion engine; and an intake air valve located between an air cleaner and a mass airflow (MAF) sensor and configured to, when open, enable flow of ambient air to the intake manifold.

An exhaust gas recirculation cooler may include a heat exchanger block including a first mounting flange, a diffuser including a second mounting flange, and at least one non-return valve arranged between the heat exchanger block and the diffuser. The exhaust gas recirculation cooler may also include a valve carrier which supports the at least one non-return valve and on which a gasket is arranged. The heat exchanger block may be connected via the first mounting flange directly to the second mounting flange of the diffuser. The valve carrier may be arranged between the heat exchanger block and the diffuser, and with the gasket may seal a sealing point between the first mounting flange and the second mounting flange. The diffuser may include an outwardly closed recess with a peripheral rim structured to accommodate the valve carrier. The rim may define the second mounting flange.