Headrest support structure

A headrest support structure, comprising:

• a stay extending downward from a headrest in use;
• a bracket configured to be coupled to a backrest so as to be formed in a tubular shape, and extending in an upward-downward direction in use;
• a tubular portion having an insertion hole in which the stay is inserted, the tubular portion being fitted into the bracket, and extending in an upward-downward direction in use;
• a first projection portion projecting from an outer peripheral surface of the tubular portion, and facing to an inner surface of the bracket;
• a second projection portion projecting from the outer peripheral surface of the tubular portion and provided lower than the first projection portion, the second projection portion facing to the inner surface of the bracket;
• and
• a connection portion located between the first projection portion and the second projection portion, the connection portion being configured to contact and connect the first projection portion and the second projection portion,
• wherein the connection portion projects outwardly in a direction away from the outer peripheral surface of the tubular portion, and
• wherein a partition wall having a dimension in a tangential direction of the tubular portion less than that of the connection portion connects the connection portion to the outer peripheral surface of the tubular portion.

A headrest support structure, comprising:

• a stay extending downward from a headrest in use;
• a bracket configured to be coupled to a backrest so as to be formed in a tubular shape, and extending in an upward-downward direction in use;
• a tubular portion having an insertion hole in which the stay is inserted, the tubular portion being fitted into the bracket, and extending in an upward-downward direction in use;
• a projection portion projecting from an outer peripheral surface of an upper part of the tubular portion, and facing to an inner surface of the bracket;
• and
• a connection portion located immediately adjacent to the projection portion, the connection portion projecting outwardly from the outer peripheral surface of the tubular portion, wherein
• an opening is formed in the tubular portion on an opposite side of the projection portion, and
• a position in a longitudinal direction of the projection portion corresponds to a position in the longitudinal direction of the opening.

A headrest support structure, comprising:

• a stay extending downward from a headrest in use;
• a bracket configured to be coupled to a backrest so as to be formed in a tubular shape, and extending in an upward-downward direction in use;
• a tubular portion having an insertion hole in which the stay is inserted, the tubular portion being fitted into the bracket, and extending in an upward-downward direction in use;
• and
• a plurality of projection portions projecting from an outer peripheral surface of the tubular portion so as to arrange the projection portions in a longitudinal direction, and facing to an inner surface of the bracket, wherein
• an interval between adjacent projection portions arranged at a middle part in the longitudinal direction of the tubular portion among the plurality of projection portions is smaller than an interval between other adjacent projection portions.