CORRUGATED AXIAL DIRECTION FILTER HAVING SIMPLE FOLDING PATTERN

PROBLEM TO BE SOLVED: To provide a corrugated axial direction filter having a simple folding pattern. SOLUTION: The corrugated axial direction filter 148 has many flow passages 178, on the like, extending in the axial direction from the front part 146 to the rear part 160. Each flow passage has an upper stream open part 186, up-and- down walls 188 and 190 and left-and-right side walls 192 and 194 both extending from the open part 186 to the rear part 160. The left-and-right side walls form triangle flow passages by tapering by facing each other as the walls extend to the rear side. The left-and-right side walls of the adjacent flow passage are made of a single and continuous sheet 130 consisting of a filter material having many folding lines including a first set folding line 136 or the like at the front part and a second set folding line 150, on the like, at the rear part in a zigzag pattern 134.