Methods and systems are provided for adjusting a substitution ratio based on water in a combustion mixture of a multi-fuel engine. In one example, a method includes adjusting a substitution ratio in response to an amount of water provided to a multi-fuel engine configured to combust a first fuel and a second fuel, the second fuel different than the first fuel.

A valve device increases or decreases a flow rate of EGR gas. The valve device includes a housing, a bypass valve body, an EGR valve body. The housing includes a first upstream passage into which the EGR gas cooled by an EGR cooler flows, a second upstream passage into which the EGR gas that bypasses the EGR cooler flows, a junction connected to each of a gas-flow downstream side of the first upstream passage and a gas-flow downstream side of the second upstream passage, and a downstream passage connected to the first upstream passage and the second upstream passage via the junction. The bypass valve body opens and closes the second upstream passage. The EGR valve body is provided in the downstream passage, rotates around an EGR valve axis.

A valve device increases or decreases a flow rate of EGR gas. The valve device includes a housing, a bypass valve body, an EGR valve body. The housing includes a first upstream passage into which the EGR gas cooled by an EGR cooler flows, a second upstream passage into which the EGR gas that bypasses the EGR cooler flows, a junction connected to each of a gas-flow downstream side of the first upstream passage and a gas-flow downstream side of the second upstream passage, and a downstream passage connected to the first upstream passage and the second upstream passage via the junction. The bypass valve body opens and closes the second upstream passage. The EGR valve body is provided in the downstream passage, rotates around an EGR valve axis.

Methods and systems are provided for diagnostics of exhaust gas recirculation (EGR) components including an EGR pressure sensor. In one example, a method may include comparing a current relationship between an output of the EGR pressure sensor and a manifold air pressure (MAP) and a pre-calibrated relation between the output of the EGR pressure sensor and the MAP to detect degradation of the EGR pressure sensor.

Methods and systems are provided for diagnostics of exhaust gas recirculation (EGR) components including an EGR pressure sensor. In one example, a method may include comparing a current relationship between an output of the EGR pressure sensor and a manifold air pressure (MAP) and a pre-calibrated relation between the output of the EGR pressure sensor and the MAP to detect degradation of the EGR pressure sensor.

An intake and exhaust system includes an engine, an intake air channel, an exhaust gas channel, an EGR channel, an EGR valve, and a control device. By adjusting an opening degree of the EGR valve, the control device executes EGR control processing to control a flowrate of a recirculating exhaust gas. An isolation valve is disposed in the EGR channel closer to the exhaust gas channel than the EGR valve is. An air admittance valve is disposed in the EGR channel closer to the exhaust gas channel than the EGR valve is and closer to the intake air channel than the isolation valve is. The control device executes learning processing to learn a relationship between an actual flowrate and a reference flowrate while the isolation valve is closed and the air admittance valve is opened. The control device executes the EGR control processing based on a learning processing result.

An intake and exhaust system includes an engine, an intake air channel, an exhaust gas channel, an EGR channel, an EGR valve, and a control device. By adjusting an opening degree of the EGR valve, the control device executes EGR control processing to control a flowrate of a recirculating exhaust gas. An isolation valve is disposed in the EGR channel closer to the exhaust gas channel than the EGR valve is. An air admittance valve is disposed in the EGR channel closer to the exhaust gas channel than the EGR valve is and closer to the intake air channel than the isolation valve is. The control device executes learning processing to learn a relationship between an actual flowrate and a reference flowrate while the isolation valve is closed and the air admittance valve is opened. The control device executes the EGR control processing based on a learning processing result.

A heat exchanger arrangement includes a heat exchanger having a front, a rear, and a side between the front and the rear, a fan arranged to direct an airflow from the front to the rear of the heat exchanger, and a screen disposed over at least the front and side of the heat exchanger and attached to a structure at or behind the rear of the heat exchanger.

A heat exchanger arrangement includes a heat exchanger having a front, a rear, and a side between the front and the rear, a fan arranged to direct an airflow from the front to the rear of the heat exchanger, and a screen disposed over at least the front and side of the heat exchanger and attached to a structure at or behind the rear of the heat exchanger.

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.