A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

An engine EGR system is provided, which includes an engine body, an intake passage, an exhaust passage and an EGR passage configured to recirculate exhaust gas as EGR gas to the intake passage. The EGR passage includes an EGR cooler and an EGR internal passage constituting the EGR passage upstream of the EGR cooler, and including a passage passing through a cylinder head. The EGR internal passage has a bent pipe part including a first bent portion at which an upstream portion of the EGR internal passage is bent away from a gas inflow port of the EGR cooler, a second bent portion located downstream of the first bent portion and bending the EGR internal passage toward the gas inflow port, and an intermediate portion connecting the first and the second bent portions by being disposed therebetween. The water-cooling passage is disposed around the bent pipe part.

A waste heat recovery (WHR) system and method for regulating exhaust gas recirculation (EGR) cooling is described. More particularly, a Rankine cycle WHR system and method is described, including an arrangement to improve the precision of EGR cooling for engine efficiency improvement and thermal management.

A waste heat recovery (WHR) system and method for regulating exhaust gas recirculation (EGR) cooling is described. More particularly, a Rankine cycle WHR system and method is described, including an arrangement to improve the precision of EGR cooling for engine efficiency improvement and thermal management.

A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

A method includes operating a spark ignition engine and flowing low pressure exhaust gas recirculation (EGR) from an exhaust to an inlet of the spark ignition engine. The method includes interpreting a parameter affecting an operation of the spark ignition engine, and determining a knock index value in response to the parameter. The method further includes reducing a likelihood of engine knock in response to the knock index value exceeding a knock threshold value.

An engine EGR system is provided. An EGR passage includes an EGR cooler, an EGR internal passage passing through a cylinder head on an upstream side of the EGR cooler, and a relay passage extending outside the cylinder head and connecting the EGR internal passage to the EGR cooler. The EGR cooler formed in a columnar shape is arranged above an intake manifold so as to locate a gas inflow port on a first end surface side and a gas outflow port on a second end surface side, and the relay passage communicates with the EGR internal passage on an external side of the engine compared to a head EGR gas exit. The EGR cooler inclines downward from the gas outflow port toward the gas inflow port, and the relay passage is connected to the gas inflow port while being bent downward toward the upstream side.

A cooling water flow control device of a cooling system for a vehicle can shorten a warm-up time of a cooling water being supplied to an exhaust gas recirculation (EGR) cooler. The cooling water flow control device includes: the EGR cooler that cools an exhaust gas supplied to an intake system of an engine using cooling water and includes an EGR cooler outlet through which the cooling water is discharged; a water pump to circulate the cooling water to the EGR cooler and the engine at an engine startup; and a direct flow path connected to a vent hole formed in the engine to guide the cooling water from the vent hole to a downstream side of an EGR cooler outlet.

A cooling water flow control device of a cooling system for a vehicle can shorten a warm-up time of a cooling water being supplied to an exhaust gas recirculation (EGR) cooler. The cooling water flow control device includes: the EGR cooler that cools an exhaust gas supplied to an intake system of an engine using cooling water and includes an EGR cooler outlet through which the cooling water is discharged; a water pump to circulate the cooling water to the EGR cooler and the engine at an engine startup; and a direct flow path connected to a vent hole formed in the engine to guide the cooling water from the vent hole to a downstream side of an EGR cooler outlet.