Patent ID: 7494400

Claim:
A method for manufacturing a multilayered gas sensor element which includes a sensor cell for measuring a specific gas concentration in a measured gas, a main body portion including a plurality of laminated ceramic substrates, and a plate heater portion generating heat in response to supply of electric power, which are integrally laminated in a predetermined order, comprising the steps of: sintering a multilayered body of green sheets forming said main body portion and said heater portion into a multilayered gas sensor element; and grinding at least both side surfaces of said multilayered gas sensor element extending in a longitudinal direction, thereby removing surface defects, wherein two side surface grinding disk grindstones, each rotating about its disk center, are disposed in parallel with each other to grind said both side surfaces of said multilayered gas sensor element extending in the longitudinal direction, and said multilayered gas sensor element is introduced into a clearance between said two side surface grinding disk grindstones to grind said both side surfaces, wherein an upper surface of said multilayered gas sensor element is substantially supported at a point when said multilayered gas sensor element is introduced into the clearance between said two side surface grinding disk grindstones to grind the side surfaces of said multilayered gas sensor element, and wherein after removing said surface defects from the sensor element, discrimination between a detective product and a non-defective product is carried out by: inspecting the processed surfaces obtained by grinding said both side surfaces with an image recognizing apparatus to check whether or not these surfaces satisfy predetermined size requirements; inspecting the presence of any chipping caused in the grinding operation; visually inspecting the presence of any growth of surface defects by supplying electric power to said heater portion; and inspecting the largeness of an insulation resistance of said multilayered gas sensor element.