Cooling fan

A cooling fan, comprising:

• a boss section connected to a rotary drive source;
• a plurality of blades integrally formed with the boss section and formed outward in a radial direction;
• and
• a cylindrical ring member configured to annularly connect end sections outside in the radial direction of the plurality of blades,
• wherein an air inlet groove is formed at an end section in an axial direction of an air suction side of the ring member, and
• wherein a lightening groove is formed at an end section in the axial direction of the air ejection side of the ring member such that a position of the lightening groove is shifted in a circumferential direction of the ring member from a position of the air inlet groove,
• wherein the lightening groove has at least two lightening grooves that are adjacent to each other in the circumferential direction and are each formed to be recessed in the axial direction with respect to a base level part of the end section of the air ejection side of the ring member, the base level part being arranged at a farthermost position in the axial direction from the air suction side, and
• wherein, in the circumferential direction, at least a center position of a bottom section of the air inlet groove is disposed within the base level part between the two lightening grooves that are adjacent to each other in the circumferential direction.

A cooling fan comprising:

• a boss section connected to a rotary drive source;
• a plurality of blades protruding outward from the boss section in a radial direction;
• and
• a cylindrical ring member configured to annularly connect the vicinities of end sections outside in the radial direction of the plurality of blades,
• wherein an air inlet groove is formed at an end section in an axial direction of an air suction side of the ring member, and
• wherein the air inlet groove is formed such that, in a circumferential direction of the ring member, a deepest bottom of the air inlet groove is positioned within a circumferential range where no blade is provided on.