Operation mechanism of side support apparatus and side support apparatus using same for vehicular seat

A side support apparatus adapted to be mounted on a vehicular seat, comprising:

• an operation mechanism of a side support apparatus adapted to be accommodated in each of a right side support portion and a left side support portion both provided at a seatback, and being movable between a support position at which sides of a body of a seat occupant is supported and an open position at which the sides of the body of the seat occupant is unsupported, the operation mechanism of the side support apparatus including a support structure including a pulley which is rotatable and being movable between the open position and the support position, a first fixing portion adapted to be fixedly provided at a seatback member, and including a first guide portion and a second guide portion, the first guide portion being provided at the first fixing portion in an extending manner to restrict a direction of a movement of the support structure and the second guide portion being provided at the first fixing portion in an extending manner in a direction that crosses with an extending direction of the first guide portion and restricting the direction of the movement of the support structure cooperatively with the first guide portion, and a drive cable, the drive cable being fixedly attached to the first fixing portion at a first end portion of the drive cable, the drive cable being engaged with an outer periphery of the pulley at an intermediate between the first end portion and a second end portion of the drive cable, wherein
• the pulley is pushed by a tensile force generated at the drive cable by pulling the drive cable at the second end portion so that the pulley is movable in the extending direction of the first guide portion and that the support structure is movable relative to the first fixing portion in a direction toward the support position;
• and
• a cable drive device including an electric motor which rotates for pulling the drive cable at the second end portion thereof when electricity is supplied, a pinion gear connected to an output shaft of the electric motor, a helical gear engaging with the pinion gear and being unmovable in a direction of a rotation axis thereof, and a screw member being movable in a direction of a rotation axis thereof and unrotatable, an outer periphery of the screw member engaging with an inner periphery of the helical gear, an end portion of the screw member being connected to the drive cable, wherein
• the screw member is moved in the direction of the rotation axis thereof via the pinion gear and the helical gear by means of driving the electric motor to rotate so that the drive cable is pulled.