Abstract: Provided is a vehicle seat assembly which can prevent a submarine phenomenon in a reliable manner, and which is simple in structure so as to allow a high level of flexibility in layout. A slip preventing member for preventing the vehicle occupant from slipping forward under the seat belt in case of an impact is supported by a fixed part of a seat so as to be pivotable between a retracted position and a raised position, and an actuator is interposed between a fixed part of said seat and a part of said slip preventing member. To retain the slip preventing member at its raised position even after the power of the power unit is all used up, the assembly further includes a lock mechanism for retaining said slip preventing member at said raised position.

Abstract: In a pretensioner device for automatically increasing a tension of a seat belt in case of a vehicle crash which uses a piston and cylinder arrangement as a power generator, a spring member resiliently urges the piston assembly in the direction of actuation so that any play that may be present in each connecting potion of the path of power transmission can be eliminated. Therefore, collision between component parts at the time of activating the power generator can be prevented, and the loss of energy which could arise from such collision can be avoided. The piston assembly may comprise a piston main body slidably received in the cylinder, and a piston rod having a base end abutting an opposing end of the piston main body and a free end projecting out of the open free end of the cylinder while the cylinder is provided with an inwardly directed radial flange for preventing the piston main body from being projected out of the cylinder.

Abstract: A submarine preventing mechanism is arrange inside a seat. The submarine preventing mechanism is provided with brackets attached to a cushion flame, links, and a submarine preventing body supported by the links. The links have first ends rotatably supported by the brackets by means of support shafts, respectively. The links have second ends located at a lower level than the support shafts. The submarine preventing body includes a first rod, a second rod, and a gas generator for generating a gas with which the second rod is pulled into the first rod at the time of a vehicle collision. If the vehicle collision occurs, the gas generator burns, generating a gas. In response to this, the second rod is pulled into the first rod. Accordingly, the links are rotated upward, raising the submarine preventing body.

Abstract: In a pre-tensioner assembly for automatically increasing a tension of a seat belt in case of a vehicle crash, an arm is pivotally attached to a base plate at its one end and to a part of a seat belt, and a cylinder and piston device is attached to the base plate to selectively rotate the arm from a rest position to an operative position. Typically, the cylinder and piston device comprises a linear cylinder having a propellant placed in a bottom end thereof. The rotary arm for displacing a buckle or other part of the seat belt can be substantially directly connected to the piston of the actuator, and because the piston rod is pushed out of the cylinder when actuating the rotary arm, the pressure receiving surface of the piston can be maximized. Therefore, the power transmission efficiency is improved, and the required amount of the propellant can be reduced with the result that the size and the cost of the assembly can be minimized.