Seat belt with an automatic unlocking device

A seat belt automatic unlocking device comprising a seat belt having an end portion with a fitting, a lock box structure which receives said seat belt end portion, a locking lever movably mounted on said lock box structure between a locked position and an unlocked position, said locking lever engaging and locking said fitting when in said locked position, said locking lever disengaging and unlocking said fitting when in said unlocked position to thereby unlock said seat belt, a mounting structure mounted on a vehicle on which the seat belt automatic unlocking device is used, connecting means connecting said mounting structure to said lock box structure, and releasable means operably connected between said mounting structure and said locking lever and operable between a release position and a non-release position, said releasable means being operable to move said locking lever to its unlocked position when said releasable means is moved to its release position, said releasable means being operable to retain said locking lever in its locked position when said releasable means is in its non-release position, said releasable means comprising a rotatably mounted drum and a rotatably mounted pulley along with a rope means extending between said drum and said pulley, said pulley being rotatable by said rope to a position to effect release of said locking lever to its unlocked position, said connecting means comprising biasing means biasingly maintaining a non-separated position between said mounting structure and said lock box structure, said biasing means permitting relative movement between said mounting structure and said lock box structure from said non-separated position to a separated position upon application of a separating force exceeding a predetermined biasing force to said biasing means, said releasable means being retained in said non-release position when said mounting structure and said lock box structure are in said non-separated position, said releasable means being moved to said released position when said mounting structure and said lock box structure are moved to said separated position, whereby said releasable means automatically unlocks said fitting to thereby unlock said seat belt after application of said separating force exceeding said predetermined biasing force.