Exhaust aftertreatment and exhaust gas recirculation systems

An exhaust aftertreatment system for an internal combustion engine comprising:

• an oxidation catalyst configured to receive an exhaust gas flow from the internal combustion engine;
• a urea injector positioned downstream of the oxidation catalyst to inject a urea flow into the exhaust gas flow;
• a mixer positioned downstream of the urea injector to mix the exhaust gas flow and the urea flow to form a mixed exhaust gas and urea flow;
• a particulate filter and catalytic reduction assembly positioned downstream of the mixer to receive the mixed exhaust and urea flow from the mixer to form a treated exhaust gas flow;
• an exhaust gas recirculation system coupled to the particulate filter to receive a portion of the treated exhaust gas flow and direct it to be mixed with a fresh air flow for the internal combustion engine, wherein the oxidation catalyst, urea injector, mixer, particulate filter and exhaust gas recirculation system are each located in an engine compartment;
• and
• an underfloor catalytic reduction assembly positioned downstream of the particulate filter and catalytic reduction assembly.

An internal combustion engine exhaust aftertreatment system comprising:

• an oxidation catalyst configured to receive an exhaust gas flow from the internal combustion engine;
• a conduit coupled to the oxidation catalyst to receive the exhaust gas flow from the oxidation catalyst and a urea flow from an injector;
• a mixer coupled to the conduit to receive the exhaust gas flow and the urea flow from the conduit and to form a mixed exhaust gas and urea flow;
• a particulate filter and catalytic reduction assembly coupled to the mixer to receive the mixed exhaust and urea flow from the mixer to form a treated exhaust gas flow;
• and
• an exhaust gas recirculation system to receive a portion of the treated exhaust gas flow and direct it to be mixed with a fresh air flow for the internal combustion engine, wherein the oxidation catalyst, urea injector, mixer, particulate filter and catalytic reduction assembly and exhaust gas recirculation system are closely coupled to the internal combustion engine.