Hermetic compressor with cylinder having elliptical inner circumferential surface, roller, and at least one vane

A hermetic compressor, comprising:

• a cylinder having an inner circumferential surface, which forms a compression chamber formed in an elliptical shape;
• a roller provided to be eccentric from the inner circumferential surface of the cylinder, and configured to change a volume of the compression chamber by being rotated;
• and
• at least one vane formed to be withdrawn towards the inner circumferential surface of the cylinder when the roller is rotated, and configured to divide the compression chamber into a plurality of spaces, wherein a position where the inner circumferential surface of the cylinder and an outer circumferential surface of the roller are closest to each other is a contact point, a line passing through the contact point and a center of the cylinder is a first center line, and lines perpendicular to the first center line and passing through a first center pint and a second center point are third and fourth center lines, the inner circumferential surface of the cylinder is divided into four quadrants and in each of the four quadrants the inner circumferential surface of the cylinder is in the shape of a different partial ellipse, wherein each of first and second partial ellipses formed above and below the first center line include two partial ellipses having a same sum of distances to two focal points for every point thereon, wherein the first partial ellipse positioned at a relatively short distance from the contact point than the first partial ellipse positioned at a relatively long distance from the contact point is formed such that a distance between two focal points thereon is relatively large, and wherein the second partial ellipse positioned at a relatively short distance from the contact point than the second partial ellipse positioned at a relatively long distance from the contact point is formed such that a distance between two focal points thereon is relatively large.