A belt tensioner for a belt retractor having a load limiter includes a pivoted pinion (14) coupled to a belt reel, a drive unit and a load transmission element (20) moved by the drive unit. The load transmission element (20) engages in the pinion (14) so as to rotate the pinion in a tensioning direction A. The load transmission element (20) is designed so that in the rotational position adopted by the pinion (14) after being rotated by the load transmission element (20) a part (20b) of the load transmission element (20) engages in the pinion (14). A method of tensioning a seat belt by means of a belt tensioner and subsequent load limitation by means of a load limiter includes moving a load transmission element (20) by a drive unit in a first direction so that the load transmission element (20) engages in a pinion (14) coupled to a belt reel (12). The rotating the pinion (14) is rotated by the moved load transmission element (20) in a tensioning direction A. When the rotation of the pinion (14) is completed it is ensured that a part (20b) of the load transmission element (20) engages in the pinion (14).

A seat belt retractor comprises a rotatable spool on which seat belt webbing is wound. The spool is rotatable in a webbing withdrawal direction and an opposite webbing retraction direction. The seat belt retractor also comprises a pretensioner actuatable to rotate the spool in the webbing retraction direction and a load-limiting system to limit a load applied to a vehicle occupant by the seat belt webbing. The load-limiting system includes a torsion bar mounted such that the torsion bar is twisted when a load in excess of a predetermined load is applied to the spool in the webbing withdrawal direction by the seat belt webbing. The bad-limiting system also includes a stop assembly actuatable to limit rotation of the spool in the webbing withdrawal direction to a predetermined number of rotations while the torsion bar is being twisted. The stop assembly is actuated upon actuation of the pretensioner.

An increase in structural complexity is suppressed in a webbing take-up device provided with a force limiter load switching mechanism and a pre-tensioner mechanism. The webbing take-up device includes a spool that takes up a webbing, a pre-tensioner mechanism that takes up the webbing onto the spool by rotating the spool in the take-up direction in a vehicle emergency, and a lock mechanism that restricts pull-out direction rotation of the spool in a vehicle emergency. The webbing take-up device further includes a force limiter mechanism that permits pull-out direction rotation of the spool at a force limiter load or greater when the lock mechanism has restricted pull-out direction rotation of the spool, and a force limiter load switching mechanism that switches a force limiter load value by being input with a portion of an actuation force that actuates the pre-tensioner mechanism.

A pretensioner for introducing a webbing wound in a spool by explosive power obtained by exploding gunpowder when an impact is applied from the outside, the pretensioner includes: a hollow cylinder having one side surface for inserting a portion of a pinion connected to the spool; a micro gas generator (MGG) mounted in an upper end portion of the cylinder and for transferring explosive power into the cylinder while gunpowder provided at the inside explodes when an impact is applied from the outside; a rack mounted in a length direction at the inside of the cylinder and having one end portion disposed toward the MGG and having the other end portion disposed opposite to the pinion and having gear teeth provided in one side surface separated not to engage with the pinion before receiving explosive power from the MGG; and a roller for receiving explosive power from the MGG and rotatably mounted at the other side surface opposite to one side surface of the cylinder in which a portion of the pinion is inserted so that the gear teeth of the rack engage with the pinion when the rack falls toward a lower end portion of the cylinder and for guiding the separated rack to move toward the pinion.

A pretensioner and a seat belt device are provided. A pretensioner includes a wire connected to webbing that restrains an occupant, a piston disposed to the wire, a cylinder that slidably accommodates the piston, a gas generator that applies driving force to the piston, and a housing that integrally connects the cylinder and the gas generator. The housing includes an insertion hole that guides the wire, a communication part that is communicated with the cylinder and the insertion hole, and a gas-supply port that supplies gas generated by the gas generator to the communication part. The pretensioner includes a wire guide disposed at a boundary portion of the insertion hole and the communication part, and a holding member that is inserted into the communication part and locked to the gas-supply port, thereby to position the wire guide.

A seatbelt pretensioner system includes a pretensioner tube in fluid communication with a gas generator and a pretensioner rod having a proximal end portion disposed toward the gas generator and a distal end portion disposed at an exit of the pretensioner tube. The pretensioner rod is disposed inside the pretensioner tube in a pre-actuation state and adapted to travel within the pretensioner tube toward a pretensioner wheel upon an actuation of the gas generator in a post-actuation state. The pretensioner rod includes a protrusion formed in a radial direction of the rod to couple with the pretensioner tube to restrict the rod from moving out from the pretensioner tube in the pre-actuation state. The pretensioner rod is configured to avoid the stripping of the rod and reduce energy consumption when the polymer rod is deformed during pretensioning.

A belt retractor having a belt reel, a safety belt which can be wound thereon to form a wound belt, a pyrotechnic belt tensioner having a drive device which is guided in a tube and can be driven to perform a drive movement, and at least one first further assembly arranged coaxially to the rotational axis of the belt reel and in series with the belt reel, a safety belt which can be wound thereon to form a wound belt, and at least one first assembly, wherein the tube has a straight linear section which extends parallel to the rotational axis of the belt reel and the longitudinal axis of the assembly and is arranged on the side of the belt reel.

In a pipe, a first corner portion, a second corner portion, and a third corner portion are formed sequentially from a guide direction upstream stream as a result of an axial direction intermediate portion of the pipe being bent in three places. The first corner portion and the second corner portion are bent in a substantially identical plane, and the third corner portion is bent in a direction deviating from the substantially identical plane. The radius of curvature of the third corner portion is set larger than the radius of curvature of the first corner portion.

A pawl member holding unit of a retractor for a seat belt includes: a cam protrusion which is provided at the other side of a torsion bar that is provided inside a spool, shares a rotation axis with the spool, and rotates together with the spool, the cam protrusion moving in accordance with the rotation of the torsion bar by an operation of a pretensioner; and a rotating member which rotates about a rotating shaft in accordance with the movement of the cam protrusion, and applies external force in a direction opposite to a direction in which a pawl member, which performs an automatic locking function, protrudes.

In a belt tensioner (10) for a seat belt comprising an elongate pressure reservoir (12), a piston (18) movably supported in the pressure reservoir (12) in the longitudinal direction to which piston pressurized fluid can be applied and which in this way can be moved in a tensioning direction (S), a mechanical thrust means (20) interacting with the piston, the thrust means interacting with a gearwheel (22) and driving the same in the case of restraint, and comprising a stop (24) on which the piston (18) abuts in the tensioning direction in a final position, it is provided that between the piston (18) and the thrust means (20) a spacer (30) in the form of a separate member is provided which is dimensioned such that in the final position of the piston (18) the thrust means (20) is urged past the stop (24) by said spacer. Furthermore there is provided a method of mounting a belt tensioner of this type.