Patent ID: 8528322

Claim:
A reductant delivery unit for selective catalytic reduction (SCR) after-treatment for vehicles, the reductant delivery unit comprising: a fluid injector constructed and arranged to be associated with an exhaust gas flow path upstream of a SCR catalytic converter, the fluid injector having a fluid inlet and a fluid outlet, the fluid inlet being constructed and arranged to receive a source of urea solution and the fluid outlet being constructed and arranged to communicate with the exhaust flow path so as to control injection of the urea solution into the exhaust gas flow path, inlet cup structure in fluid communication with the fluid inlet of the fluid injector, the inlet cup structure being mounted for movement, a shield fixed with respect to the fluid injector and surrounding at least portions of the fluid injector and the inlet cup structure, and a spring engaged between a portion of the inlet cup structure and the shield, wherein, when the urea solution freezes in the fluid injector and expands near the fluid inlet of the injector, the inlet cup structure is constructed and arranged to move towards the injector inlet, against the bias of the spring, to accommodate the frozen urea solution, with the spring returning the inlet cup structure to an initial position once the frozen urea solution melts.