Cooling apparatus

A cooling apparatus comprising:

• a coolant passage provided in a device to be cooled, the coolant passage being configured in such manner that coolant passes through the coolant passage, wherein
• the coolant passage comprises
• a first wall surface,
• a second wall surface opposite the first wall surface;
• a plurality of first ribs, and
• a plurality of second ribs, each second rib having a tip part defining a recess, wherein
• the first wall surface and the second wall surface define a wall height therebetween,
• the first ribs protrude from the first wall surface toward inside of the coolant passage a first height and extend in a first direction,
• the second ribs protrude from the second wall surface toward the inside of the coolant passage a second height and extend in a second direction crossing the first direction,
• the first ribs and the second ribs extending in the first direction and the second direction respectively are disposed alternately when viewed in at least one direction of the second ribs,
• the first ribs and the second ribs are arranged on the first wall surface and the second wall surface on an exhaust side of an intake port passing member,
• when viewed in a normal direction of the first wall surface, the first ribs and second ribs at least partially overlap each other, and
• when viewed in a direction parallel to the first wall surface, a combined height of the first height and the second height is greater than the wall height such that each first rib extends into the recess of a respective second rib of the plurality of second ribs,
• whereby the liquid coolant is restricted from passing through gaps between the first ribs and the second ribs in a straight path.