Electrically heated catalyst

An electrically heated catalyst which is arranged in an exhaust passage of an internal combustion engine, said catalyst comprising:

• a heat generation element that is electrically energized to generate heat so that a catalyst is heated by the generation of heat;
• a case that receives said heat generation element therein;
• an insulating member that is arranged between said heat generation element and said case to support said heat generation element and to insulate electricity;
• electrodes that are connected to said heat generation element through an electrode chamber which, in the final assembly of said electrically heated catalyst, is a space located between an inner wall surface of said case and an outer peripheral surface of said heat generation element, and which has a side wall surface formed by said insulating member, said electrodes supplying electricity to said heat generation element;
• and
• a communication passage that has one end thereof directly connected to said electrode chamber, and the other end thereof connected to a portion of an exhaust system of the internal combustion engine, which is other than a portion thereof in which the electrically heated catalyst is arranged, and that provides communication between a portion of an exhaust system of the internal combustion engine, which is other than a portion thereof in which the electrically heated catalyst is arranged, and said electrode chamber.