Seat slide device for vehicles

1. A vehicle seat slide device comprising:

a lower rail;

an upper rail that is movably attached to the lower rail and supports a seat;

a lock spring that is attached to the upper rail, has a lock part engaging with the lower rail to restrict movement of the upper rail, and is formed in an annular shape; and

an unlocking member that is attached to the upper rail and displaces the lock spring to disengage the lock spring and the lower rail to clear the restriction on the movement of the upper rail, wherein

the unlocking member is positioned more inside than the lock spring as seen in both a longitudinal direction and a width direction of the upper rail, and

the unlocking member extends upwards and downwards from a portion of the unlocking member between two portions of the lock spring in the width direction of the upper rail.

2. The vehicle seat slide device according to claim 1 , wherein the unlocking member is attached more backward than the lock part of the lock spring as seen in a front-back direction of the vehicle.

3. The vehicle seat slide device according to claim 1 , wherein the unlocking member comprises:

a first member having a convex portion and rotatable about a first axis; and

a second member having an engagement portion engageable by the convex portion and rotatable about a second axis different from the first axis.