Ceramic heater device and method for manufacturing the device

A ceramic heater device having a structure in which an axial ceramic heater is arranged in a metallic cylinder member so that its leading end protrudes from the leading end of said metallic cylinder member and in which said metallic cylinder member and said ceramic heater are fixed to each other with a solder layer interposed between their inner circumference and outer circumference respectively, wherein:

• in said ceramic heater, a diametrically smaller portion having a smaller diameter than that of the remaining portion in said metallic cylinder member is formed at a portion located in said metallic cylinder member and corresponding to the portion proximate to the leading end of said metallic cylinder member;
• and
• a solder layer is disposed at said diametrically smaller portion for preventing sliding out of at least a portion of said ceramic heater toward the leading end with respect to said metallic cylinder member.

A ceramic heater device having a structure in which an axial ceramic heater is arranged in a metallic cylinder member so that its leading end protrudes from the leading end of said metallic cylinder member and in which said metallic cylinder member and said ceramic heater are fixed to each other with a solder layer interposed between their inner circumference and outer circumference respectively, wherein:

• at least one recess is formed in the outer circumference of said ceramic heater at a portion located in said metallic cylinder member and corresponding to the portion proximate to the leading end of said metallic cylinder member, wherein a solder layer is disposed in said at least one recess for preventing sliding out of at least a portion of said ceramic heater toward the leading end with respect to said metallic cylinder member.

A method for manufacturing a ceramic heater device having a structure in which an axial ceramic heater is arranged in a metallic cylinder member so that its leading end protrudes from the leading end of said metallic cylinder member, comprising the steps of:

• forming a convergent taper portion at the leading end of said ceramic heater;
• and
• press-fitting said ceramic heater into said metallic cylinder member, starting with the leading end of the ceramic heater, to such a position that the taper starting point of said taper portion does not go beyond the leading end of said metallic cylinder member.