Catalyst device

A catalyst device arranged in an exhaust passage of an internal combustion engine mounted on a vehicle, the catalyst device comprising:

• a catalyst that purifies exhaust;
• a heating element that generates heat when energized to heat the catalyst;
• a case that includes a pipe accommodating the catalyst and the heating element;
• a connecting pipe connected to an end of the case at an upstream side in a direction in which exhaust flows through the exhaust passage;
• and
• a guide pipe connected to an end of the connecting pipe at an upstream side in the exhaust direction and having a smaller diameter than the case, wherein:
• the end of the case at the upstream side in the exhaust direction is an electrically insulative portion and projects further upstream from an end of the heating element at an upstream side in the exhaust direction,
• a portion where the connecting pipe and the case are connected includes a coupling portion where the connecting pipe is coupled to an outer circumferential surface of the case, and a pipe structure in which the connecting pipe, at an upstream side of the coupling portion in the exhaust direction, is separated from the case in a radial direction so as to overlap and encompass the end of the case,
• the catalyst device further comprises a temperature difference inducing structure that induces a state in which the connecting pipe is relatively lower in temperature than the end of the case, and
• the temperature difference inducing structure includes a heat shield encompassing an outer circumferential surface of the connecting pipe and having an opening in part of a portion opposing the outer circumferential surface of the connecting pipe.