Linear seat belt pretensioner

• US 8,528,987 B2
• Filed: 01/30/2012
• Issued: 09/10/2013
• Est. Priority Date: 01/30/2012
• Status: Active Grant

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Cahill, Timothy J., Burrow, Jon E.
• Primary Examiner(s): WHITE, RODNEY BARNETT
• Application Number:
  US13/361,206
• Publication Number:
  US 20130193741A1
• Time in Patent Office: 589 Days
• Field of Search: 297/480
• US Class Current: 297/480
• CPC Class Codes: B60R 22/1955 Linear actuators

Abstract

A linear seat belt pretensioner (10, 110, 210) has a frame (12; 112, 113; 212, 213) and an axial cavity (24, 60; 124, 160; 232) rigidly connected to the frame (12; 112, 113; 212, 213), a gas generator (20, 120, 220) in fluid communication with the axial cavity (24, 60; 124, 160, 232), and a piston (40, 140, 240) movably arranged in the axial cavity (24, 60; 124, 160; 232). An actuating profile (42, 142, 242) movable with the piston (40, 140) pulls a length of seat belt webbing (38, 238) into the frame (12; 112, 113; 212, 213) that corresponds to twice the piston stroke (D). The pretensioner device having a locking ramp arrangement (66, 70; 266, 290, 292) configured to form a one-way clutch allowing an increase and resisting a reduction of the length of belt webbing (38, 238) received by the pretensioner (10, 110, 210).

Claims

1. A linear pretensioner for use as part of a motor vehicle seat belt restraint system of the type mountable to a motor vehicle structure and acting on a seat belt, the pretensioner upon being activated, pretensioning the seat belt to reduce slack in the seat belt, the linear pretensioner comprising:

a frame configured to be fastened to a vehicle;

a body rigidly connected to the frame, the body including an axial cavity having one axial end formed by a movable closure and one fixedly closed axial end;

an actuating assembly arranged to seal the axial cavity and to slide relative to the body in an axial direction, thereby forming the movable closure and expanding the axial cavity, the actuating assembly including an actuating profile movable with the actuating assembly in the axial direction along an actuation path;

a gas generator in fluid communication with the axial cavity and configured to generate a gas pressure in the axial cavity that causes the actuating assembly to slide in the axial direction;

a guide arrangement configured to receive a length of belt webbing being a part of the seat belt restraint system, the length of belt webbing being guided with respect to the frame in a manner that the belt webbing extends around the actuating profile and crosses the actuation path,

the actuating profile being configured to abut the length of belt webbing and to lengthen the length of belt webbing received by the guide arrangement upon deployment of the gas generator by axially moving the belt webbing within the guide arrangement along the actuation path so as to shorten the length of the seat belt outside the guide arrangement,

the pretensioner device having a locking ramp arrangement configured to form a one-way clutch allowing an increase of the length of belt webbing received by the guide arrangement and resisting a reduction of the length of belt webbing received by the guide arrangement,

wherein the locking ramp arrangement comprises two angled slots on the frame, the angled slots forming a ramp, and a locking wedge having two sliding tabs configured to slide in the angled slots, in a manner allowing a movement of the belt webbing into the guide arrangement and resisting a movement of belt webbing out of the guide arrangement.

2. The pretensioner of claim 1, further comprising that the locking wedge has a toothed surface extending parallel to the belt webbing and having a plurality of slanted teeth configured to engage the belt webbing during a movement of the belt webbing outward from the guide arrangement.

3. The pretensioner of claim 1, further comprising that the gas generator is connected to the actuating profile and movable therewith, and that a fluid connection through the actuating profile connects the axial cavity with the gas generator.

4. The pretensioner of claim 3, further comprising that the frame has an axially extending opening for electrical conductors leading from the gas generator to an electronic control unit.

5. The pretensioner device of claim 1, wherein the axial cavity is formed by a cylinder and the actuating assembly comprises a piston slidably arranged in the cylinder.

6. The pretensioner of claim 5, wherein the actuating profile is formed as a part of the piston.

7. The pretensioner of claim 5, wherein the actuating profile is a separate part connected to the piston.

8. The pretensioner of claim 1, wherein a travel of the actuating profile along the actuation path by a distance lengthens the length of the seat belt webbing received by the guide arrangement by twice the distance.

9. The pretensioner of claim 1, further comprising that the actuating assembly has axial guide elements configured to guide the actuating profile along the actuation path.

10. The pretensioner of claim 1, wherein at least a portion of the axial cavity is formed by a cylinder partially inserted into a block.

11. The pretensioner of claim 10, wherein the cylinder is made of metal.

12. The pretensioner of claim 10, wherein the block is made of metal and comprises a bore forming a part of the axial cavity.

13. The pretensioner of claim 10, further comprising an axial collar formed on the block, the axial collar being crimped or caulked to axially secure the gas generator inside the axial cavity.

14. The pretensioner of claim 1, wherein the guide arrangement comprises a slot on one radial side of the frame and an attachment bar on a radially opposite side of the frame.

15. A pretensioner for use as part of a motor vehicle seat belt restraint system of the type mountable to a motor vehicle structure and acting on a seat belt, the pretensioner upon being activated, pretensioning the seat belt to reduce slack in the seat belt, the pretensioner comprising:

a frame configured to be fastened to a vehicle;

a gas generator configured to generate a gas pressure upon receiving an electronic trigger signal;

an actuating assembly configured to be operated by the gas pressure generated by the gas generator and to pull a length of a seat belt webbing into the frame; and

a locking ramp arrangement acting on the seat belt webbing, configured to form a one-way clutch allowing movement of the seat belt webbing into the frame and resisting a movement of the seat belt webbing out of the frame,

wherein the locking ramp arrangement comprises two angled slots on the frame, the angled slots forming a ramp, and a locking wedge having two sliding tabs configured to slide in the angled slots, in a manner allowing a movement of the belt webbing into the guide arrangement and resisting a movement of belt webbing out of the guide arrangement.