Sliding structure for vehicle seat

1. A sliding structure for a vehicle seat, the sliding structure configured to attach the vehicle seat slidably in an anteroposterior direction to a vehicle body, the sliding structure comprising:

at least one seat positioning portion configured to position the seat in the anteroposterior direction and a seat slide support portion configured to support the seat movably in the anteroposterior direction,

wherein the seat positioning portion includes a positioning hole portion including a plurality of positioning holes aligned in the anteroposterior direction, and a positioning pin attached to a seat frame and configured to be movable to a projecting position where the positioning pin projects to one of the plurality of positioning holes to be engageable therewith, and to a withdrawn position where the positioning pin is withdrawn from the positioning holes;

wherein the positioning pin enables the seat to be positioned in the anteroposterior direction at the projecting position, and the positioning pin allows the seat to slide in the anteroposterior direction at the withdrawn position; and

wherein the seat slide support portion includes: a plurality of seat attachment portions located at four corners of a bottom of the seat, respectively; a plurality of seat support portions attached to a chassis frame so as to correspond to the seat attachment portions, respectively; and a plurality of seat guide portions configured to be attached at the seat attachment portions, respectively, and each of the seat guide portions being movable in the anteroposterior direction relative to the corresponding one of the seat support portions,

wherein each of the seat attachment portions is attached to the seat frame, extends in the anteroposterior direction parallel to a seat support surface and is provided, substantially at the center, with an elongated hole that extends in the anteroposterior direction and vertically penetrates the seat attachment portion, and

wherein each of the seat guide portions has a fastening bolt, a washer, and a collar,

the washer being positioned on an upper surface of the respective seat attachment portion and having a diameter that is larger than a hole width of the elongated hole in a vehicle width direction,

the collar being fitted and inserted in the elongated hole with an axis thereof being aligned in the vertical direction, the collar having a vertical height that is larger than a height of the seat attachment portion, and a diameter that is slightly smaller than the hole width of the elongated hole,

the fastening bolt being inserted through an inner diameter portion of the collar with a head portion thereof being positioned on the washer and fastened to the seat support portion.

2. The seat sliding structure according to claim 1 , wherein the seat positioning portion is located below a front portion of the seat.

3. The seat sliding structure according to claim 1 , wherein the positioning pin is movable in a vertical direction.

4. The seat sliding structure according to claim 1 , wherein the positioning pin is movable in a vehicle width direction.

5. The seat sliding structure according to claim 1 , wherein

the seat frame has a cross member extending in a vehicle width direction, and

the positioning pin is attached to the cross member.

6. The seat sliding structure according to claim 1 , wherein each of the seat attachment portions has a slide member at least at one of a contact portion with the seat support portion and a contact portion with the seat guide portion.

7. The seat sliding structure according to claim 1 , wherein a plurality of seat positioning portions is provided.