The exhaust gas recirculation (EGR) system provided herein utilizes a crossover (X) valve that is selectively activated at the direction of the electronic control module (ECM) to mix the high temperature (HT) and low temperature (LT) circuits of the EGR system under certain predetermined operating conditions. Thus, HT circuit fluid (at engine temperatures) is selectively fed into the LT circuit fluid (at ambient temperatures) to heat certain LT circuit components that are normally cooled by the LT circuit before starting the low pressure (LP) EGR in certain cold cycles. When this heating is finished, the X valve is closed to provide normal HT circuit/LT circuit fluid separation. The X valve can be controlled using a rotational actuator or the like. To avoid exposing the LT circuit to the high revolution-per-minute (RPM) operating conditions of the HT circuit, a HT bypass mechanism is provided.

A cooling system is mounted on an internal combustion engine equipped with an EGR device including an EGR passage. The cooling system includes: an intercooler disposed in the intake passage; an EGR cooler disposed in the EGR passage; a condensed water discharger configured to discharge condensed water generated in the EGR cooler from the EGR passage; a radiator configured to cool a first coolant to or below a dew point of the EGR gas flowing into the EGR cooler; a first circulation flow path configured to circulate the first coolant in the order of the radiator, the EGR cooler, and the intercooler; and a pump disposed in the first circulation flow path and configured to circulate the first coolant such that an outlet gas temperature of the EGR cooler is equal to or lower than the dew point of the EGR gas flowing into the EGR cooler.

A cooling system is mounted on an internal combustion engine equipped with an EGR device including an EGR passage. The cooling system includes: an intercooler disposed in the intake passage; an EGR cooler disposed in the EGR passage; a condensed water discharger configured to discharge condensed water generated in the EGR cooler from the EGR passage; a radiator configured to cool a first coolant to or below a dew point of the EGR gas flowing into the EGR cooler; a first circulation flow path configured to circulate the first coolant in the order of the radiator, the EGR cooler, and the intercooler; and a pump disposed in the first circulation flow path and configured to circulate the first coolant such that an outlet gas temperature of the EGR cooler is equal to or lower than the dew point of the EGR gas flowing into the EGR cooler.

An exhaust gas recirculation (EGR) system with a diesel particulate filter (DPF) incorporated before the EGR cooler to filter the particulate matter from the EGR before entering the air intake. With the DPF installed before the EGR cooler soot buildup in all EGR components and air intake track is reduced or eliminated. Installing the DPF before the EGR cooler allows the DPF to be in passive regeneration while the vehicle's engine is in operation, extending the life and maintenance interval of the DPF. Alternatively, the DPF may be installed after the EGR cooler, reducing or eliminating soot buildup in the EGR valve and air intake.

A surge suppression device for suppressing surge in an exhaust turbine-type turbocharger includes: a high-pressure tank configured to accumulate high-pressure gas with a higher pressure than atmospheric pressure; a high-pressure gas injection line connecting the high-pressure tank and an upstream intake passage on an upstream side of a compressor of the turbocharger; an on-off valve configured to open and close the high-pressure gas injection line; and a control device configured to control the on-off valve on the basis of a relationship between a pressure ratio of the compressor of the turbocharger and an intake flow rate.

The subject matter of this specification can be embodied in, among other things, a gas mixer that includes a convergent-divergent nozzle comprising a convergent portion and a divergent portion and defining a first gas flow path, an air housing comprising an air inlet configured to supply air to the first gas flow path upstream of the convergent-divergent nozzle, a gas housing defining a second gas flow path and including a first gas inlet configured to receive a secondary gas and allow the secondary gas into a second gas flow path, and a gas nozzle positioned parallel to and centrally within the first gas flow path in a convergent portion of the convergent-divergent nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the divergent portion.

The subject matter of this specification can be embodied in, among other things, a gas mixer that includes a convergent-divergent nozzle comprising a convergent portion and a divergent portion and defining a first gas flow path, an air housing comprising an air inlet configured to supply air to the first gas flow path upstream of the convergent-divergent nozzle, a gas housing defining a second gas flow path and including a first gas inlet configured to receive a secondary gas and allow the secondary gas into a second gas flow path, and a gas nozzle positioned parallel to and centrally within the first gas flow path in a convergent portion of the convergent-divergent nozzle, the gas nozzle configured to supply the secondary gas to the first gas flow path upstream of the divergent portion.

Methods and systems are provided for an exhaust system. In one example, the exhaust system includes an aftertreatment device and a recirculation passage. A recirculation valve is positioned in the recirculation passage and configured to control an amount of recirculated exhaust gas flowing through the recirculation passage to the aftertreatment device. The exhaust system further includes a diverter valve configured to control a flow of engine exhaust gases to different portions of a catalyst of the aftertreatment device.

Methods and systems are provided for an exhaust system. In one example, the exhaust system includes an aftertreatment device and a recirculation passage. A recirculation valve is positioned in the recirculation passage and configured to control an amount of recirculated exhaust gas flowing through the recirculation passage to the aftertreatment device. The exhaust system further includes a diverter valve configured to control a flow of engine exhaust gases to different portions of a catalyst of the aftertreatment device.

A vehicular internal combustion engine system includes an internal combustion engine and an electric intake air supply device. The internal combustion engine is shifted into a stoichiometric combustion mode, and a lean combustion mode. The electric intake air supply device is driven by an on-vehicle battery, and employed to contribute a part of intake air quantity at least under a specific operating condition when in the lean combustion mode. A control method includes: determining a requested electric energy of the electric intake air supply device for a shift into the lean combustion mode in response to a shift from a stoichiometric combustion operation region into a lean combustion operation region; and continuing the stoichiometric combustion mode, without operation of the electric intake air supply device, when the on-vehicle battery is in an insufficient state of charge with respect to the requested electric energy.