Seat belt pretensioner
View Patent ↗A pretensioner for a three point vehicle safety restraint seat belt, has a mounting for one end of the seat belt. The mounting is a first member fixed to a load bearing part of the vehicle. A second member is attached to the end of the seat belt. A means is provided for moving the second member relative to the first member in a pretensioning direction in response to activation of a crash sensor. The mounting may be a flexible cable that functions as a slider bar. A piston-cylinder force reservoir may be used either to pull the slider bar via a carriage mounted on a rail, or to pull the cable directly. Return motion is preferably inhibited. The arrangement provides a space saving pretensioner suitable for two-door vehicles while allowing access to the vehicle rear.
1. A pretensioner for a three point seat belt, comprising:
a mounting for one end of the seat belt, the mounting comprising a first member adapted to be fixed to a load bearing part of the vehicle and a second member comprising a flexible member connecting the second member to the end of the seat belt webbing and having one end mounted to a fixed part of the vehicle, the flexible member functioning as a slider bar; and
means for moving the second member translationally relative to the first member in a pretensioning direction in response to activation of a crash sensor, the first member comrprising a rail and the second member comprising a carriage mounted for sliding movement on the rail.
2. The pretensioner for a three point seat belt according to claim 1 wherein the flexible member comprises a cable arranged in a loop form profile.
3. The pretensioner for a three point seat belt according to claim 1 wherein the means for moving comprises a piston connected to the second member and a cylinder housing the piston such that pyrotechnic activation of the means for moving the piston along the cylinder.
4. The pretensioner for a three point seat belt according to claim 2 wherein the means for moving comprises a piston connected to the second member and a cylinder housing the piston such that pyrotechnic activation of the means for moving the piston along the cylinder.
5. The pretensioner for a three point seat belt according to claim 2 wherein the cable is held by releasable clips in a loop form profile.
6. The pretensioner for a three point seat belt according to claim 2 wherein the cable is coated with an elastomeric plastic material.
7. The pretensioner for a three point seat belt according to claim 2 wherein the cable is enclosed in a tube of an elastomeric plastic material.
8. The pretensioner for a three point seat belt according to claim 3 wherein the piston and the cylinder are located above the rail.
9. The pretensioner for a three point seat belt according to claim 4 wherein the piston and the cylinder are located above the rail.
10. A pretensioner for a three point seat belt according to claim 1 wherein the first member comprises means for restraining motion of the second member in a non-pretensioning direction, the restraining means comprising ratchet teeth incorporated in the first member and at least one cooperating tooth incorporated in the second member.
11. A pretensioner for a three point seat belt, comprising:
a mounting for one end of the seat belt, the mounting comprising a first member adapted to be fixed to a load bearing part of the vehicle and a second member comprising a cable arranged in a loop, in the general form of a slider bar, connecting the second member to the end of the seat belt webbing and having one end mounted to a fixed part of the vehicle, the flexible member functioning as a slider bar; and
a means for moving the second member translationally relative to the first member in a pretensioning direction in response to activation of a crash sensor, the means for moving comprising a piston connected to the second member and a cylinder housing the piston such that pyrotechnic activation of the means for moving moves the piston along the cylinder;
the first member comprising a rail having ratchet teeth and the second member comprising a carriage mounted for sliding movement on the rail, the carriage having at least one cooperating tooth for restraining motion of the second member in a non-pretensioning direction.
12. A pretensioner for a three point seat belt, comprising:
(a) a mounting for one end of the seat belt, the mounting comprising
(i) a rail having ratchet teeth adapted to be fixed to a load bearing part of the vehicle;
(ii) a carriage mounted for sliding movement on the rail, the carriage having at least one cooperating tooth for restraining motion of the second member in a non-pretensioning direction;
(iii) a flexible cable arranged in a loop in the general form of a slider bar, the cable being reinforced by an elastomeric plastic, the cable connecting the carriage to the end of the seat belt webbing and having one end mounted to a fixed part of the vehicle, the flexible cable functioning as a slider bar; and
(b) a means for moving the carriage translationally relative to the rail in a pretensioning direction in response to activation of a crash sensor, the means for moving comprising a piston connected to the second member and a cylinder housing the piston such that pyrotechnic activation of the means for moving moves the piston along the cylinder.
13. The pretensioner for a three point seat belt according to claim 12 wherein the piston and the cylinder are located above the rail.
14. A pretensioner for a three point seat belt, comprising:
a mounting for one end of the seat belt, the mounting comprising a first member adapted to be fixed to a load bearing part of the vehicle and a second member comprising a flexible member connecting the second member to the end of the seat belt webbing and having one end mounted to a fixed part of the vehicle, the flexible member functioning as a slider bar; and means for moving the second member translationally relative to the first member in a pretensioning direction in response to activation of a crash sensor, the first member comprising means for restraining motion of the second member in a non-pretensioning direction, the restraining means comprising ratchet teeth incorporated in the first member and at least one cooperating tooth incorporated in the second member.