Scroll structure of centrifugal compressor and centrifugal compressor

A scroll structure of a centrifugal compressor having a scroll passage formed in spiral shape and having a larger dimension in an axial direction of the centrifugal compressor at a winding end portion of the scroll passage than at a winding start portion of the scroll passage, comprising:

• a tongue portion separating the scroll passage from an outlet passage connected to a downstream side of the scroll passage at a most downstream position of the scroll passage in a passage connecting portion where the winding start portion and the winding end portion intersect;
• and
• a ridge portion protruding from an inner peripheral surface of the scroll passage on an axially downstream side of the centrifugal compressor toward an axially upstream side of the centrifugal compressor, wherein a protruding height of the ridge portion protruding toward the axially upstream side gradually increases toward the tongue portion from a starting position that is located upstream from the tongue portion in the scroll passage, and wherein a circumferential length of the tongue portion of the centrifugal compressor from the winding start portion to the tongue portion is longer than the protruding height,
• wherein the protruding height in a position at an angle of 4 degrees in a circumferential direction of the centrifugal compressor from the tongue portion toward an upstream side of the scroll passage is 10% or less of a height dimension of the scroll passage at the winding start portion along an axial direction of the centrifugal compressor.

A scroll structure of a centrifugal compressor having a scroll passage formed in spiral shape and formed so that a cross-sectional area of the scroll passage increases from a winding start portion of the scroll passage to a winding end portion of the scroll passage, comprising:

• a tongue portion separating the scroll passage from an outlet passage connected to a downstream side of the scroll passage at a most downstream position of the scroll passage in a passage connecting portion where the winding start portion and the winding end portion intersect;
• and
• a ridge portion protruding from an inner peripheral surface of the scroll passage on an axially downstream side of the centrifugal compressor toward an axially upstream side of the centrifugal compressor, wherein a protruding height of the ridge portion protruding toward the axially upstream side gradually increases toward the tongue portion from a starting position that is located upstream from the tongue portion in the scroll passage,
• wherein the protruding height is 30% or less of a height dimension along an axial direction of the centrifugal compressor at a position where the cross-sectional area of the scroll flow passage is a smallest.

A scroll structure of a centrifugal compressor having a scroll passage formed in spiral shape, comprising:

• a tongue portion separating the scroll passage from an outlet passage connected to a downstream side of the scroll passage at a most downstream position of the scroll passage in a passage connecting portion where a winding start portion and a winding end portion of the scroll passage intersect;
• and
• a ridge portion protruding from an inner peripheral surface of the scroll passage on an axially downstream side of the centrifugal compressor toward an axially upstream side of the centrifugal compressor, wherein a protruding height of the ridge portion protruding toward the axially upstream side gradually increases toward the tongue portion from a starting position that is located upstream from the tongue portion in the scroll passage,
• wherein a curvature radius of a curve connecting an apex of the ridge portion defining the protruding height from the tongue portion to the starting position is located on the axially upstream side, and
• wherein the curvature radius gradually increases from the tongue portion to the starting position in at least a portion of the apex.