Air foil journal bearing

An air foil journal bearing comprising:

• a bump foil provided inside a bearing housing, formed in a circumferential direction, and coupled to the bearing housing;
• and
• a top foil provided inside the bump foil, formed in the circumferential direction, and configured such that one end and the other end of the top foil based on the circumferential direction are disposed adjacent to each other, top foil keys extend radially outward from the two opposite ends based on the circumferential direction, and the top foil keys are inserted into a key groove of the bearing housing,
• wherein one end and the other end of the top foil based on the circumferential direction are disposed with a step difference in the radial direction,
• wherein one end of the top foil is disposed inward of the other end of the top foil in the radial direction when a direction in which the top foil extends from one end to the other end is identical to a rotation direction of a rotor disposed inside the top foil and configured to rotate,
• wherein a length La of a first top foil key connected to one end of the top foil based on the circumferential direction is equal to a length Lb of a second top foil key extending from the other end of the top foil based on the circumferential direction,
• wherein one end of the top foil based on the circumferential direction is disposed adjacent to the first top foil key, and
• wherein one end of the top foil based on the circumferential direction and an inner end of the first top foil key based on the radial direction are connected by an inclined portion.

An air foil journal bearing comprising:

• a bump foil provided inside a bearing housing, formed in a circumferential direction, and coupled to the bearing housing;
• and
• a top foil provided inside the bump foil, formed in the circumferential direction, and configured such that one end and the other end of the top foil based on the circumferential direction are disposed adjacent to each other, top foil keys extend radially outward from the two opposite ends based on the circumferential direction, and the top foil keys are inserted into a key groove of the bearing housing,
• wherein one end and the other end of the top foil based on the circumferential direction are disposed with a step difference in the radial direction,
• wherein one end of the top foil is disposed inward of the other end of the top foil in the radial direction when a direction in which the top foil extends from one end to the other end is identical to a rotation direction of a rotor disposed inside the top foil and configured to rotate,
• wherein a length La of a first top foil key extending from one end of the top foil based on the circumferential direction is longer than a length Lb of a second top foil key connected to the other end of the top foil based on the circumferential direction, and
• wherein a stepped portion is formed with a step difference radially inward from the other end of the top foil based on the circumferential direction in a direction opposite to a rotation direction of the rotor.