Particulate matter detecting device

A particulate matter detecting device comprising:

• a sensor element having a unidirectionally long flat-plate-shaped element substrate, at least one pair of measurement electrodes arranged on one end portion side of said element substrate, a heater electrode arranged on said one end portion of said element substrate, a measurement electrode lead terminal arranged on the other end portion of said element substrate, a heater electrode lead terminal arranged on said the other end portion of said element substrate, a measurement electrode wiring for electrically connecting said measurement electrodes and said measurement electrode lead terminal, and a heater electrode wiring for electrically connecting said heater electrode and said heater electrode lead terminal;
• a hollow columnar lead terminal cover member which is formed of ceramics with electrical insulation property, and in which a penetration portion that penetrates from one end face to the other end face is formed and said sensor element is inserted into said penetration portion so that said measurement electrode lead terminal and said heater electrode lead terminal of said sensor element are at least partially arranged inside said penetration portion;
• and
• a detecting device external cylinder that is formed of a metal material for storing said lead terminal cover member having said sensor element inserted into said penetration portion in a state that said one end portion of said sensor element is exposed outside from one end face of the external cylinder, wherein:
• said penetration portion formed in said lead terminal cover member includes a first penetration portion in which a size of a cross section perpendicular to a penetration direction corresponding to a size of a cross section of said sensor element perpendicular to a longitudinal direction in a range with a predetermined length from said one end face of said lead terminal cover member, and a second penetration portion which penetrates from said first penetration portion to said the other end face of said lead terminal cover member and which is formed so that a size of a cross section perpendicular to the penetrating direction is larger than that of said first penetration portion;
• and
• an electrical insulating sealant is filled in a gap between said second penetration portion and said sensor element inserted into said second penetration portion so that said sensor element and said lead terminal cover member are fixed.