Electrically heated catalyst device

Abstract

An electrically heated catalyst device has a cylindrical outer skin part and a cell formation part. A pair of electrodes formed on the outer skin park faces relative to each other in a radial direction of the honeycomb structural body. An electrode terminal is formed on the corresponding electrode in an outer radial direction of the honeycomb structural body. A length edge line of each electrode is inclined to a virtual reference line at a predetermined angle. The virtual reference line is a virtual line defined on the outer circumferential surface of the outer skin part and is parallel to the axial direction of the honeycomb structural body. The electrode terminals are formed at a predetermined interval in the axial direction of the honeycomb structural body to make an angle of less than 180° when viewed from one end surface perpendicular to the axial direction of the honeycomb structural body.

What is claimed is: 
     
         1 . An electrically heated catalyst device comprising:
 a honeycomb structural body comprising an outer skin part having a cylindrical shape and a cell formation part, the cell formation part being covered with the outer skin part;   a pair of electrodes formed on an outer circumferential surface of the outer skin park, one electrode in the pair of the electrodes facing the other electrode in a radial direction of the honeycomb structural body; and   a pair of electrode terminals formed on the pair of the electrodes toward outside in a radial direction of the honeycomb structural body,   wherein length edge lines of one electrode and length edge lines of the other electrode extend on the outer circumferential surface of the outer skin part from one end surface to the other end surface of the honeycomb structural body in an axial direction of the honeycomb structural body so that the length edge lines of the electrodes are inclined to a virtual reference line at a predetermined angle, the length edge lines being a longitudinal part in an outline of each electrode, the virtual reference line being a virtual line defined on the outer circumferential surface of the outer skin part, which is parallel to the axial direction of the honeycomb structural body,   an interval between the electrodes in the pair formed on the outer circumferential surface of the outer skin part of the honeycomb structural body measured along the circumferential direction of the honeycomb structural body is constant,   the electrode terminals in the pair are formed at a circumferential center of the electrodes so that the electrode terminals keep at a predetermined interval measured in the axial direction of the honeycomb structural body, and the electrode terminals in the pair make an angle of less than 180 degrees (180°) at a radial center of the honeycomb structural body when measured on the outer circumferential surface of the outer skin part and viewed down one end surface which is perpendicular to the axial direction of the honeycomb structural body.   
     
     
         2 . The electrically heated catalyst device according to  claim 1 , wherein an insulation layer made of electrical insulation material is formed on the outer skin part of the honeycomb structural body other than in area on which the electrodes are formed. 
     
     
         3 . The electrically heated catalyst device according to  claim 1 , wherein the electrode terminals in the pair make an angle of not more than 150° when viewed from one end surface of the honeycomb structural body, and the end surface is perpendicular to an axial direction of the honeycomb structural body. 
     
     
         4 . The electrically heated catalyst device according to  claim 1 , wherein each of the length edge lines of each of the electrodes is inclined to the virtual reference line at an angle of not more than 45 degrees (45°). 
     
     
         5 . The electrically heated catalyst device according to  claim 1 , wherein the honeycomb structural body has a relationship of:
     D+E ×sin θ1 ≧R/ 2,
   where D is a width of each of the electrodes measured along a circumferential direction of the outer skin part, E is a longitudinal length of each of the length edge lines of each of the electrodes, θ 1  is an angle of the length edge line of each of the electrodes to the virtual reference line, and R is a circumference of an outer circumference of the honeycomb structural body in the circumferential direction C.   
     
     
         6 . The electrically heated catalyst device according to  claim 1 , wherein a distance on the outer skin part between the electrodes in the pair measured along the axial direction of the honeycomb structural body is larger than a distance on the outer skin part between the electrodes along the circumferential direction of the honeycomb structural body. 
     
     
         7 . The electrically heated catalyst device according to  claim 1 , wherein the honeycomb structural body is made of porous ceramics including SiC. 
     
     
         8 . The electrically heated catalyst device according to  claim 3 , wherein the electrode terminals in the pair make an angle of 80 degrees (80°) when viewed from one end surface of the honeycomb structural body, the end surface is perpendicular to an axial direction of the honeycomb structural body. 
     
     
         9 . The electrically heated catalyst device according to  claim 4 , wherein each of the length edge lines of each of the electrodes is inclined to the virtual reference line at an angle of 42 degrees (42°).