Combustion cylinder structure for oil burner

A combustion cylinder structure for an oil burner comprising:

• a multi-cylindrical combustion means including a perforated inner cylindrical member, an outer cylindrical member arranged outside said inner cylindrical member and an outermost cylinder arranged outside said outer cylindrical member,
• said outer cylindrical member being formed at the lower portion thereof with a plurality of through-holes of a smaller diameter and at the middle and upper portions thereof with a plurality of through-holes of a larger diameter,
• said outermost cylinder including a heat-impermeable cylinder arranged so as to surround said lower portion of said outer cylinder member and to heat-permeable cylinder arranged on said heat-impermeable cylinder so as to surround said middle and upper portions of said outer cylindrical member;
• and,
• a collar provided at the upper portion of said heat-impermeable cylinder with a first collar portion which extends inwardly from said heat-impermeable cylinder toward an area of said outer cylindrical member which is a boundary area between said through-holes of smaller diameter and said through-holes of larger diameter,
• said heat-permeable cylinder being put on said collar,
• said collar having a second collar portion which is bent upwardly at the distal end of the collar to form a cylindrical section which is spaced from said outer cylindrical member to define a vertically extending gap of substantially uniform width between said second collar portion and said outer cylindrical member,
• said second collar portion extending upwardly opposite to said boundary area of said outer cylindrical member,
• said first collar portion being formed with through-holes,
• and said second collar portion extending upwardly for a distance sufficient to prevent turbulent flow between said outer cylindrical member and said heat-permeable cylinder by causing smooth upward flow of air flowing through said vertically extending gap and of air flowing through the through-holes of said first collar portion during a small amount of combustion in said oil burner.