Seat belt pretensioner

A seat belt pretensioner for a seat belt device in a vehicle, the pretensioner including a frame, a ball housing attached to the frame and a drive wheel located within the ball housing. A spool is connected to the drive wheel and is fixed to one end of a seat belt webbing so that the webbing may be wound around the spool. The pretensioner further includes a pipe connected to the ball housing and a gas generator connected to the pipe. At least one power transmission element is carried in the pipe and is driven by gas provided from the gas generator to contact the drive wheel and rotate the spool to retract the seat belt. A seal member is located between the at least one power transmission element and the gas generator. The seal member is sized to plug the pipe at an inlet to the ball housing.

GENERAL DESCRIPTION

The present disclosure relates to a seat belt system. In particular, a seat belt pretensioner that includes a system for locking the spool of the pretensioner.

The anchor of a seat belt system of a vehicle may comprise a pretensioner device (e.g., a pyrotechnic driven device) for tensioning the seat belt. The pretensioner is provided for removing slack in the webbing during an emergency, such as a vehicle collision. A typical lap seat belt pretensioner may use a cable driven mechanism in order to pull the seat belt to remove slack during emergency situations. During the pretensioning event, the high-pressure operating gas may leak due to tolerances between elements of the cable system. The leakage of gas may reduce the effectiveness of the pretensioner and may release hot, pressurized gas into the vehicle environment.

As described herein, a superior functioning alternative to the cable type pulling pretensioner mechanism utilizes spherical-shaped members (e.g., ball shaped) that act as a power transmission system for rotating a seat belt webbing spool during an emergency. The power transmission system may include a pretensioner tube or pipe configured as a pressure container. A gas generator is disposed at one end of the pretensioner pipe and during an emergency, such as a vehicle collision, a hot, high-pressure operating gas is supplied from the gas generator to the inside of the pretensioner pipe. The operating gas forces a piston to slide along the inside of the pretensioner pipe and the piston presses against one of the spherical shaped members forcing one or more of the spherical shaped members to engage teeth of a drive wheel thereby rotating the spool in order to tension the seat belt. The tensioning of the seat belt may be configured to occur immediately after an impact of the vehicle to enhance occupant restraint performance. The pretensioning system described herein provides for pushing the ball shaped power transmission members which provides for better gas sealing over the cable type pretensioners which use the generated gas to pull the cable and tension the seat belt webbing.

Accordingly, it is desired to provide a push type pretensioner system for a seat belt system.

SUMMARY

According to one disclosed embodiment, a pretensioner for a seat belt device in a vehicle is disclosed herein. The pretensioner includes a frame, a ball housing attached to the frame, and a drive wheel located within the ball housing. A rotating spool is connected to the drive wheel and is fixed to one end of a seat belt webbing so that the webbing may be wound around the spool. The spool is rotatably mounted to the frame and configured to rotate in a pretensioning direction in response to an acceleration of the vehicle greater than a predetermined high acceleration. A pipe is connected to the ball housing and a gas generator connected to the pipe. The pretensioner includes at least one ball shaped power transmission element carried in the pipe that is driven by gas provided from the gas generator when the pretensioner device is activated so that the at least one power transmission element can contact the drive wheel to thereby rotate the spool to retract the seat belt. The seal member is located between the at least one power transmission element and the gas generator. The seal member is configured to travel through the pipe after the pretensioner device is activated and is sized to plug the pipe at an inlet to the ball housing.

The pretensioner may include a ratchet ring disposed adjacent to the ball housing and connected to the spool. A spring may be provided to bias the ratchet ring towards the ball housing. According to one embodiment, the ratchet ring is configured to engage the ball housing when the webbing is pulled in an engagement direction so that the spool is prevented from rotating in a direction that allows extraction of the seat belt webbing. The ball housing comprises a ramp configured to allow the at least one transmission element to travel in a spiral path in the ball housing. The ratchet ring includes ratchet teeth and the ball housing includes housing teeth. The ratchet teeth ride over the housing teeth when the drive wheel rotates in the pretensioning direction to cause retraction of the seat belt. The ratchet teeth and the housing teeth engage when the webbing is pulled in an engagement direction opposite to the pretensioning direction.

According to another embodiment, the pretensioner may include a first ratchet wheel disposed adjacent to the spool and located at a first end of the spool, and pawl attached to the frame is configured to engage the first ratchet wheel. The first ratchet wheel is configured to engage the pawl when the webbing is pulled in an engagement direction, wherein the engagement direction is opposite to the pretensioning direction. The pretensioner may include a second ratchet wheel disposed adjacent to the spool and located at a second end of the spool. The pawl may extend the length of the spool and is configured to engage the second ratchet wheel; wherein the pawl includes two free ends and wherein each of the free ends engages one of the first and second ratchet wheels when the webbing is pulled in the extraction direction.

According to a disclosed embodiment a pretensioner for a lap seat belt of a seat belt device in a vehicle is provided. The pretensioner includes a frame, a ball housing attached to the frame, a drive wheel located within the ball housing, and a rotating spool connected to the drive wheel and configured to be fixed to one end of a seat belt webbing so that the webbing may be wound around the spool. The spool is rotatably mounted to the frame and is configured to rotate in a pretensioning direction in response to an acceleration of the vehicle greater than a predetermined high acceleration. The pretensioner includes a ratchet ring disposed adjacent to the ball housing and connected to the spool, and a spring configured to bias the ratchet ring towards the ball housing. The pretensioner includes at least one ball shaped power transmission element carried in a pipe that is driven by gas provided from a gas generator when the pretensioner device is activated so that the at least one power transmission element can contact the drive wheel to thereby rotate the spool to retract the seat belt. The ratchet ring is configured to engage the ball housing when the webbing is pulled in an engagement direction so that the spool is prevented from rotating in a direction that allows extraction of the seat belt webbing.

The ball housing may include a ramp configured to allow the at least one transmission element to travel in a spiral path in the ball housing. An end cap may be connected to the ball housing and the at least one transmission element is configured to move towards the end cap in the spiral path of the ball housing. The ratchet ring may include ratchet teeth and the ball housing includes housing teeth, and wherein the ratchet teeth ride over the housing teeth when the drive wheel rotates in the pretensioning direction to cause retraction of the seat belt. The ratchet teeth and the housing teeth may engage when the webbing is pulled in an engagement direction opposite to the pretensioning direction. The pretensioner may include at least one seal member located between the at least one power transmission element and the gas generator, wherein the seal member is configured to prevent gas from leaking out of the pipe. The seal member may be configured to travel through the pipe after the pretensioner device is activated and is sized to plug the pipe at an inlet to the ball housing.

According to another disclosed embodiment, a seat belt pretensioner for a seat belt device in a vehicle is provided. The pretensioner includes a frame, a ball housing attached to the frame, a drive wheel located within the ball housing, and a spool rotationally locked to the drive wheel and configured to be fixed to one end of a webbing so that the webbing may be wound around the spool. The spool is rotatably mounted to the frame and is configured to rotate in a pretensioning direction in response to an acceleration of the vehicle greater than a predetermined high acceleration. A first ratchet wheel is disposed adjacent to the spool and located at a first end of the spool. A pawl is attached to the frame is configured to engage the first ratchet wheel. The pretensioner also includes at least one power transmission element carried in a pipe that is driven by gas provided from a gas generator when the pretensioner device is activated so that the at least one power transmission element can contact the drive wheel to thereby rotate the spool in the pretensioning direction. The first ratchet wheel is configured to engage the pawl when the webbing is pulled in an engagement direction, wherein the engagement direction is opposite of the pretensioning direction.

The ball housing may include a ramp configured to allow the at least one transmission element to travel in a spiral path in the ball housing. An end cap may be provided wherein the at least one transmission element is configured to move towards the end cap in the spiral path of the ball housing. The pretensioner may further include a second ratchet wheel disposed adjacent to the spool and located at a second end of the spool, wherein the pawl extends the length of the spool and is configured to engage the second ratchet wheel. The pawl may include two free ends and each of the free ends may be configured to engage one of the first and second ratchet wheels when the webbing is pulled in the extraction direction opposition of the pretensioning direction. The pawl may be biased toward the ratchet wheels by a spring retaining clip.

DETAILED DESCRIPTION

Described herein is a lap belt pretensioner system of a seat belt system of a vehicle. The pretensioning system includes a frame, a spool rotationally connected to the frame and configured to wind a webbing of a seat belt system of a vehicle. A ball housing may be attached to the frame, and a drive wheel may be located within the ball housing and connected to the spool. A pipe is connected to a gas generator and contains a plurality of power transmission members. The power transmission members are preferably spherical or ball shaped. In an alternative embodiment, the plurality of power transmission members described herein may be replaced by a single rod shaped power transmission member. The rod shaped member may comprise a malleable plastic material.

The pipe is attached to the ball housing. The gas generator is configured to release gas to push the ball shaped power transmission members into the ball housing in order to rotate the drive wheel. The drive wheel rotates the spool in a tensioning direction, which winds the webbing around the spool and retracts the webbing in order to remove slack from the webbing securing a passenger of the vehicle.

The pretensioner may include a rotating ratchet ring that is disposed coaxially and rotationally locked relative to the spool. The ratchet ring is disposed adjacent to the ball housing and biased towards the ball housing by a wave spring. The ball housing includes housing teeth that project towards the ratchet ring. The ratchet ring includes ratchet ring teeth complimentary to and interlocking with the ball housing teeth in one direction (i.e., the engagement direction). The interface between the ratchet ring teeth and ball housing teeth is configured to allow the ratchet ring, drive wheel, and spool to rotate in a pretensioning direction while preventing the ratchet ring, drive wheel, and spool from rotating in the engagement direction after the teeth of the ratchet ring and ball housing are engaged to thereby prevent the seat belt webbing from being extracted from the spool.

According to a second embodiment of a lap pretensioner described herein, instead of a single ratchet wheel as described above, a pair of ratchet wheels are disposed on opposite ends of the spool and are rotationally locked to the spool. A pawl is attached to the frame and extends between two flanges of the frame. The pawl is biased by a spring retaining clip configured to hold the pawl onto the frame and bias the pawl to the pair of ratchet wheels. The ratchet wheels and the pawl interface so that the pawl does not restrict rotating of the ratchet wheels in the seat belt tensioning direction. Thus, the spool may be driven by the rotation of the drive wheel when the transmission members are pushed down the pipe and into the ball housing. However, the pawl prevents the ratchet wheels from rotating in the engagement direction to thereby prevent the spool from rotating and the webbing from being extracted.

FIGS.1and2illustrate an exemplary embodiment of a vehicle10having an interior compartment that is configured to provide seating to an occupant11. The vehicle10includes a seat belt assembly12that is configured to secure (e.g., restrain) the occupant11when seated in a seat assembly of the vehicle10.

As shown, the seat belt assembly12(e.g., seat belt system, occupant restraint device, etc.) includes a seat belt13(e.g., a webbing) having a shoulder portion13aand a lap portion13bthat are separated by a tongue member16that is configured to selectively (e.g., releasably) engage a buckle mechanism14. The lap portion13bof the seat belt13is configured to generally wrap around the lap of the occupant11to restrain the lower portion of the occupant11during a dynamic vehicle event. The lap portion13bmay have an end disposed opposite the tongue member16that is configured to be fixed, such as, for example, to a pretensioning device18(e.g., a pretensioner). The shoulder portion13aof the seat belt13is configured to generally wrap around the torso and shoulder of the occupant to restrain the torso or thorax of the occupant during a dynamic vehicle event.

The shoulder portion13amay have an end13ddisposed opposite the tongue member16that is configured to be secured, for example retractably secured, to a retractor19. The seat belt13is configured to wind (e.g., retract) and unwind (e.g., extract) about the retractor19. The retractor19may be integrated with the seat or attached to the vehicle10. The seat belt assembly12may also include a guide15(e.g., a D-ring, etc.), for guiding the shoulder portion13aof the seat belt13. The seat belt assembly12may have any suitable configuration and may include fewer or additional components to restrain and secure an occupant in a vehicle, and the example disclosed herein is not limiting.

The pretensioner18is configured to pretension the seat belt13, such as during a dynamic vehicle event (e.g., a frontal impact), by removing an amount of slack between the seat belt13and the occupant11that is present at the onset of the dynamic vehicle event. For example, the pretensioner18may retract the webbing13by rotating a spool to thereby displace the end of the seat belt13that is connected to the spool a corresponding distance to remove slack between the occupant11and the seat belt13. The seat belt assembly12may include one or more sensors (not shown) configured to detect an emergency event (e.g. vehicle collision). Although described herein as an anchor mounted pretensioner (e.g. anchor17), the disclosed embodiments of the pretensioner may be mounted to the portion of the seat belt webbing13connected to the buckle14.

FIG.3shows a first embodiment of the pretensioner18. The pretensioner18includes a spool21rotatably attached to a pretensioner frame20. The webbing13is affixed to the spool21and is configured to be wound around the spool21when the spool rotates in a retracting direction. The webbing13may be affixed to the spool21by any known and suitable attaching mechanisms in the art of seat belt systems. A ball housing22is disposed on the opposite end of the frame and may be fastened onto the frame20. A ratchet ring26and a wave spring27are located between the ball housing22and the spool21. The ratchet ring26includes ratchet teeth26aconfigured to engage ball housing teeth22ain one direction (i.e. engagement direction). The ratchet teeth26aand the ball housing teeth22aare configured to pass (e.g., slide past) each other in the other direction (i.e. pretensioning direction). The wave spring27biases the ratchet ring26towards the ball housing teeth22a. The ball housing22is attached to a pipe23which houses a gas generator25at the upstream end.

FIG.4is a cross sectional view of the pretensioner18. The pipe23houses a plurality of power transmission members24. Each of the power transmission members24is, for example, a ball or spherical body. The power transmission members24are, for example, formed of a material with a lower specific gravity than iron (e.g., aluminum, aluminum alloy, or the like). Adopting a material with a lower specific gravity than iron enables weight reduction of the power transmission member24. In other embodiments, the power transmission members24may be formed of an iron based material such as stainless steel. It should be noted that the shape of the power transmission member24is not limited to spherical body. For example, it may have other shapes such as a cylindrical body, a prismatic body, and oval rotational body. In another embodiment, a rod or extended body may be employed, such as a polymer based rod. The gas generator25is configured to supply a gas into the pipe23. The gas is typically a high-temperature high-pressure gas, and the pipe is generally formed of an iron based material (stainless steel or the like) that is configured to withstand the heat and provide resistance to the high pressure.

The power transmission members24are configured to rotate a drive wheel28located within the ball housing22. The drive wheel28is rotationally locked to the spool21. The ratchet ring26is disposed radially outwards towards the drive wheel28and is configured to be rotationally locked to the drive wheel28via a spline located externally on the drive wheel28. Thus, the spool21, the ratchet ring26, and the drive wheel28are rotationally locked to each other. The ball housing22includes a ramp22bfor guiding the power transmission members24onto an outer periphery of the drive wheel28. The wave spring27and the ratchet ring26may be disposed coaxially relative to each other and relative to the rotation axis of the drive wheel28. An end cap30may be disposed at one end of the ball housing22. The end cap30encloses the ball housing22keeping the power transmission members24and gas sealed within the pretensioner18.

During a pretensioning event (e.g., a dynamic impact event involving the vehicle), the gas generator25is actuated to supply gas into the pipe23. The power transmission members24are pushed by the gas to move within the pipe23and into the ball housing22. The power transmission members24are configured to engage and rotate the drive wheel28. Rotation of the drive wheel28causes a corresponding rotation of the spool21in order to remove slack from the webbing13. A seal member29is provided between the power transmission members24and the gas generator25in order to prevent gas from leaking out of the pipe23. The seal29travels a limited distance with the power transmission members24and is provided to plug the pipe23at the inlet to the ball housing22. The pipe23is configured to enclose a high-temperature high-pressure gas, it is generally formed of an iron based material (stainless steel or the like) that is configured to provide heat and pressure resistance. The pipe23may include a threaded end configured to be threaded onto the ball housing22.

The ratchet teeth26aare each configured to engage one of the housing teeth22ain the engagement direction while configured to pass by each other when the drive wheel28is driven in the pretensioning direction. The wave spring27biases the ratchet ring26towards the housing teeth22a. During the pretensioning event, the drive wheel28is rotated by the power transmission members24in the pretensioning direction. Rotation of the drive wheel28in the pretensioning direction allows the ratchet ring teeth26ato ride over the housing teeth22ain order to remove slack from the webbing. The ratchet ring teeth26aengage the housing teeth22aand prevent the spool from rotating due to occupant loading from the sudden vehicle deceleration. The occupant load on the webbing13imparts a force to the spool21in the engagement direction and allows the ratchet ring teeth26ato engage and lock onto the housing teeth22a, holding the drive wheel28and the spool21together, preventing extraction of the webbing13as shown inFIG.7.

FIG.5is an isometric view of the pretensioner18including a transparent pipe23that is included for demonstrative purposes to facilitate viewing of the power transmission members24and gas generator25housed in the pipe23.

As shown inFIG.6, the drive wheel has a plurality of projections28athat are formed and extend along an outer circumferential surface of the drive wheel28. The plurality of projections28aare configured to be engaged with the power transmission members24. It should be noted that the shape, number, and disposition of the projections28amay be designed according to the structure of the power transmission members24, and are not limited to the structure shown in the drawings. The external spline28bof the drive wheel engages the internal spline26bof the ratchet ring26and allows the ratchet ring26to be rotationally locked with the drive wheel28. Ramp22bis disposed in the ball housing22and circumferentially extends along the interior wall22din a spiral pattern. Ramp22bguides the power transmission members24spirally towards the end cap30as shown inFIG.8.

FIGS.9A-9Dshow the components of the locking mechanism that includes the ratchet ring26, ball housing22, drive wheel28, and spool21. The ratchet ring26includes the internal spline26bthat locks and engages with the external spline28bof the drive wheel28, allowing the ratchet ring26to be rotationally locked to the drive wheel28. The drive wheel28includes an internal spline28cthat engages an external spline21aof the spool21, allowing the drive wheel28to be rotationally locked to the spool21. This configuration rotationally locks the ratchet ring26, the drive wheel28, and the spool21together. The ratchet ring teeth26aare configured to engage ball housing teeth22ain the pretensioning direction (i.e. the direction in which the webbing of the seat belt is wound around the spool). The configuration of the teeth26aand22athat is shown in the drawings is only exemplary and may be configured such that the engagement direction of the teeth26aand22acoincides with the rotation direction of the extraction or pulling of the webbing of the spool. The ball housing22may include a ball housing projection22cconfigured to be engaged to the frame20. The ramp22bis disposed on the interior wall of the ball housing22and is configured to provide a spiral path for the power transmission members24.

FIG.10shows a second embodiment of a pretensioner118. The pretensioner118may be located similarly in the vehicle10in place of pretensioner18as shown inFIGS.1and2. Pretensioner118includes a similar drive mechanism to the embodiment described above. The pretensioner118may include a pawl101attached to a frame120. The pawl101extends longitudinally across the frame between two flanges120aand120bof the frame120. A spool121is configured to be rotationally disposed on the frame120. A webbing13is attached to the spool and is configured to be wound around the spool121during a pretensioning event. The pawl101is rotatably connected to the frame120and biased toward the spool121via a spring retaining clip128attached to the frame120. A pair of ratchet wheels126and127are disposed at the longitudinal ends of the spool121and located between the spool121and the respective flanges120aand120b. The ratchet wheels126and127are rotationally locked onto the spool121and may be coaxial with the axis of rotation of the spool121. Similar to the first embodiment described above, during a pretensioning event, power transmission members (not shown) inside pipe123are pushed by gas provided by a gas generator125into the ball housing122to rotate a drive wheel (not shown) in the pretensioning direction.

During operation of the pretensioner118, the drive wheel rotates the spool121in the pretensioning direction and winds the webbing13around the spool121in order to remove slack in the webbing from the passenger. The pawl101includes two free ends that are configured to engage the ratchet wheels126and127when occupant loading from the sudden vehicle deceleration pulls the webbing and imparts a force in the engagement direction on the spool. The spring retaining clip128biases the pawl101against the ratchet wheels126and127. The teeth on the ratchet wheels ride over the free ends of the pawl101to thereby allow the ratchet wheels126and127to rotate in the pretensioning direction (i.e. when the webbing is retracted). The ratchet wheels126,127ride over the pawl101during pretensioning. However, after pretensioning, the free ends of the pawl101engage the ratchet wheels126and127to prevent the spool from rotating in the engagement direction thereby preventing the webbing13from being extracted once the pawl engages the ratchet wheels. Details of the ball housing122, pipe123, drive wheel (inside ball housing122), frame120, and spool121are similar to counterparts shown and described in the first embodiment.