Reductant injection in an exhaust system

An engine exhaust system comprises an exhaust pipe 18 having a bend and an interior surface, and is in fluid communication with a catalyst downstream of the bend. An injector 12 is mounted to the exterior of the exhaust pipe and has an injector tip 28 which is disposed within the interior of the exhaust pipe at the bend, for injecting liquid reductant into the exhaust pipe. A shield member 4 is mounted in the exhaust pipe, spaced apart from its interior surface, and comprises a generally tubular or frustoconical structure having an open proximal end 14 and an open distal end 16, the proximal end being disposed such that the injector tip is inside the shield member, and the distal end is disposed at or towards a centre line 26 of the exhaust pipe. A vane 6 is mounted in relation to the shield member, and is arranged to direct a proportion of exhaust flow from upstream of the bend in a substantially arcuate path into the proximal end of the shield member.