Patent Description:
The present invention relates generally to a seat belt restraint system for restraining an occupant of a vehicle, and more particularly to a seat belt retractor for such a system having a spool, a primary locking system, and an auxiliary locking system.

Seat belt retractors are a standard component of vehicle belt restraint systems and have a spool (spindle) for receiving seat belt webbing. The spool is used to wind up and store the webbing. Upon detection of a potential accident situation as indicated by vehicle deceleration or seatbelt webbing extraction, the spool is locked against rotation to restrain the occupant via the seat belt. Recently, retractors have been designed with one or more load limiting elements which are structured to allow the spool to rotate and pay out the seat belt webbing upon reaching predetermined webbing load levels between the occupant and seat belt during a restraint event. In this manner, the restraint force imposed on the occupant can be limited in a controlled manner, providing desired load limitation characteristics.

One or more torsion bars within the spool are commonly used as load limiting elements. In an impact condition, one end of the torsion bar is locked to the retractor frame while the other end is coupled with the retractor spool. The bar section between the attachment points undergoes elastic and plastic torsional deflection, enabling torsion controlled, relative rotation between the spool and the retractor frame. The resulting controlled extraction of webbing during a restraint event serves to limit belt loading acting on the vehicle occupant.

One type of multi-stage load limiting retractor uses a multi-stage torsion bar or a system of torsion bars. The multi-stage torsion bar is essentially two torsion bars that are axially aligned and joined at respective ends. The appropriate stage or portion of the torsion bar may be selectively coupled to provide a secondary load limiting characteristic as desired.

Presently available torsion bar type load limiting retractors generally operate satisfactorily. However, there are additional design goals and objectives desired for further improvement. One such design goal may be to reduce complexity, cost, and/or packaging size. Another such design goal may be to provide a mechanism for improving retractor strength during a restraint event. From the document <CIT> it is known a retractor having a spool with a tooth disc, which provides a locking mechanism by a radial displacement of the spool and an engagement of the teeth of the tooth disc with locking teeth at the frame.

The present invention provides a vehicle seat belt assembly having a seat belt retractor with a spool rotatable with respect to a retractor frame, and storing a seat belt webbing wrapped thereon. The retractor also includes a primary locking mechanism for selectively locking the spool with respect to the retractor frame to provide vehicle occupant restraint. The retractor further includes an auxiliary locking mechanism for selectively locking the spool with respect to the retractor frame upon a predetermined restraint load acting on the spool.

Further embodiments of the present invention include the auxiliary locking mechanism having a plurality of locking teeth defining a portion of the retractor frame and an auxiliary locking surface defining a portion of the spool.

Furthermore the spool undergoes radial displacement in response to the predetermined restraint load acting on the spool, thereby permitting engagement between the plurality of locking teeth and the auxiliary locking surface.

Furthermore, the present invention includes a deformable bearing at least partially positioned between the at least one auxiliary locking tooth and the auxiliary locking surface to substantially prevent engagement between the at least one auxiliary locking tooth and the auxiliary locking surface until the predetermined restraint load acting on the spool. The deformable bearing includes one or more sidewall substantially perpendicular to the bearing surface and configured to abut one or more walls of the retractor frame. Additionally, the retractor may include more than one deformable bearing.

Further embodiments of the present invention may also include a load limiting element coupled with the spool, wherein the primary locking mechanism selectively locks the spool with respect to the retractor frame at least partially via the load limiting element. The present invention may also include a spool rotation limiter configured to selectively engage at least one of the load limiting element and the spool and selectively restrict relative rotation between the load limiting element and the spool.

With particular reference to <FIG> and <FIG>, retractor assembly <NUM> in accordance with a first embodiment of this invention is illustrated. The retractor assembly includes generally: a retractor frame <NUM>, a spool assembly <NUM> with a spool element <NUM> rotable with respect to the retractor frame <NUM>, a load limiting element such as a torsion bar <NUM> coupled with the spool element <NUM>, a primary locking mechanism <NUM> for selectively locking the spool element <NUM> with respect to the retractor frame <NUM> via the load limiting element <NUM>, and an auxiliary locking mechanism <NUM> for selectively locking the spool element <NUM> with respect to the retractor frame <NUM>.

The spool assembly <NUM> includes the spool element <NUM>, which forms an outer generally cylindrical surface <NUM> adapted for engagement with an end of a length of seat belt webbing <NUM>, and enables multiple wraps of the seat belt webbing <NUM> to be rolled onto and stored on the spool element <NUM>. One end of spool element <NUM> forms a bearing surface <NUM> which is held within suitable bushings or bearing elements carried by a retractor frame <NUM>. For example, the retractor frame <NUM> includes first and second framewalls 19a, 19b and a deformable bearing <NUM> is positioned between the first framewall 19a and the spool bearing surface <NUM>. A torsion spring cap <NUM>, which is coupled with the first sidewall 19a, houses a retraction spring <NUM> that engages with slit <NUM> of the spool to retract slack from the seat belt webbing <NUM>.

The opposite end of a spool element <NUM> is coupled with a profile head <NUM> that includes a bearing stub <NUM> which is held within suitable bushings or bearing elements directly or indirectly supported by the retractor frame <NUM>. For example, the bearing stub <NUM> of the profile head <NUM> may be coupled with a tread head (not shown) that is well known in the art. The surface 14a of the spool element <NUM> abuts a surface 22a of the profile head <NUM> with sufficient force and with sufficient respective coefficients of friction that the spool element <NUM> and the profile head <NUM> rotate together during certain conditions, such as during all or most periods of non-collision condition operation.

The profile head <NUM> defines a generally cylindrical shaped bore <NUM> for receiving a coupler end <NUM> such that the profile head <NUM> and the coupler end <NUM> rotate together. For example, one or both of the bore <NUM> and coupler end <NUM> may each include splines that engage each other and prevent slippage or other relatively rotational movement between the respective components. The profile head <NUM> is in working connection with a primary locking mechanism <NUM>, which restrains rotation of the spool element <NUM> upon detection of a locking event, as is known in the art. For example, upon detection of a locking event, the primary locking mechanism <NUM> locks the profile head <NUM> with respect to the retractor frame side wall 19b, thereby restraining rotation of spool element <NUM>, in a manner to be described below.

The retractor assembly <NUM> may also include a pretensioner device <NUM>, such as a rotopretensioner device. Rotopretensioner devices are known and may incorporate a series of elements such as ball masses or a polymer rod element (not shown) driven to engage a sprocket wheel under gas pressure provided by a gas generator. However, the invention claimed herein may operate with or without a pretensioner device <NUM>.

The retractor assembly <NUM> shown in the figures also includes a load limiting element, such as a torsion bar <NUM> with a first end <NUM> coupled with the profile head <NUM> via the coupler end <NUM> and a second end <NUM> coupled with the spool element <NUM>. The profile head <NUM>, the coupler end <NUM>, the torsion bar <NUM>, and the spool element <NUM> (at the end <NUM>) may be rotationally fixedly coupled with each other such as to completely or substantially prevent rotational movement at the connection points therebeween. For example, one or both of the first end <NUM> of the torsion bar <NUM> and a bore <NUM> within the coupler end <NUM> may each include splines that engage each other and prevent slippage or other relative rotational movement between the respective components. Similarly, one or both of the second end <NUM> of the torsion bar <NUM> and a bore <NUM> within the spool element <NUM> may each include splines that engage each other and prevent slippage or other relative rotational movement between the respective components. The profile head <NUM>, the coupler end <NUM>, the torsion bar <NUM>, and the bore <NUM> of the spool element <NUM> need not include splines to limit rotational movement; on the contrary the components may use any suitable components and/or configuration to limit or prevent the above-described relative rotation movement at the connection points therebetween. The spool load limiting element is not necessary for operation of the invention described herein.

During normal operation, the torsion bar <NUM> and spool element <NUM> rotate about a normal operation central axis 36a. However, under certain conditions discussed in more detail below, the spool element <NUM> and/or the torsion bar <NUM> may undergo radial displacement such that they rotate about a displaced central axis 36b. In other words, due to restraint loads reaching a predetermined level, the spool element <NUM> longitudinal axis becomes displaced or skewed from its normal position.

The retractor assembly <NUM> may also include a spool rotation limiter <NUM> configured to selectively engage the torsion bar <NUM> and/or the spool element <NUM> to selectively prevent relative rotation between the torsion bar <NUM> and the spool element <NUM>. For example, after a predetermined number of turns (full or partial) between the torsion bar <NUM> first end <NUM> and second ends <NUM>, the spool rotation limiter <NUM> will lock the spool element <NUM> to the profile head <NUM> and prevent further rotation of the torsion bar <NUM>. As a more specific example, the spool rotation limiter <NUM> shown in <FIG> includes a threaded nut <NUM> that is threadedly-coupled with a threaded portion <NUM> of the coupler end <NUM>. Upon rotational deformation of the torsion bar <NUM> (when the second end <NUM> rotates with respect to the first end <NUM>), the spool element <NUM> rotates with respect to the coupler end <NUM> and the threaded nut <NUM> travels along the threaded portion <NUM> of the coupler end towards a profile head wall <NUM>. After a certain number of rotations, determined by the thread pitch and the length of the threaded portion, the threaded nut <NUM> engages the profile head wall <NUM> and locks or substantially locks the spool element <NUM> and the profile head <NUM>, thereby preventing further rotation of the torsion bar <NUM>. The spool rotation limiter <NUM> is not necessary for operation of the invention described herein.

The retractor assembly <NUM> may also include an auxiliary locking mechanism <NUM> for selectively locking the spool element <NUM> with respect to the retractor frame <NUM> upon a a predetermined restraint load acting on the spool. For example, the auxiliary locking mechanism <NUM> shown in <FIG> includes at least one auxiliary locking tooth for selectively engaging an auxiliary locking surface to restrain relative movement between the frame and the spool. As a more specific example, the auxiliary locking mechanism <NUM> shown in <FIG> includes a plurality of auxiliary locking teeth <NUM> that selectively engage an outside cylindrical surface of the spool element <NUM>, namely auxiliary locking surface <NUM>, upon reaching the predetermined restraint load acting on the spool. The auxiliary locking mechanism <NUM> shown in <FIG> also includes the deformable bearing <NUM> positioned between the auxiliary locking surface <NUM> of the spool element <NUM> and the auxiliary locking teeth <NUM> to prevent engagement between the auxiliary locking surface <NUM> and the auxiliary locking teeth <NUM> while the deformable bearing <NUM> is intact (i.e., before the reaching the predetermined restraint load). In other words, when the deformable bearing <NUM> remains intact and in position, it generally prevents contact between the auxiliary locking surface <NUM> of the spool element <NUM> and the auxiliary locking teeth <NUM>, thereby allowing the spool element <NUM> to rotate within bearing surface 21a without the auxiliary locking teeth <NUM> engaging or directly contacting the spool element <NUM>.

The above-referenced predetermined restraint load acting on the spool may be at least partially facilitated by engagement of the spool rotation limiter <NUM> locking the spool element <NUM> and the profile head <NUM>. For example, upon engagement of the spool rotation limiter <NUM>, the restraint load acting on the spool element <NUM> may increase to the point that the predetermined restraint load is reached. Additionally, when the predetermined restraint load is reached, the spool element <NUM> may be radially displaced, as discussed above.

During normal vehicle operation, in which the profile head <NUM> is not locked, spool assembly <NUM> is permitted to freely rotate with respect to the retractor frame <NUM> about bearing <NUM> and bearing stub <NUM>. For example, belt webbing <NUM> may be protracted from the retractor (typically by a vehicle occupant) in the direction <NUM> shown in <FIG> or retracted (typically by the retractor spring <NUM>) in the opposite direction. This operation permits certain types of movement of the vehicle occupant during normal operating conditions, providing desirable comfort and convenience features.

During a locking event, the spool assembly <NUM> is generally restricted or prevented from seat belt <NUM> extraction in the direction <NUM>. For example, the profile head <NUM> is locked with respect to the retractor frame <NUM> to restrict seatbelt webbing <NUM> extraction.

In one type of locking event, a routine locking event, the seat belt webbing <NUM> extraction speed or extraction acceleration may fall outside prescribed limits, thereby indicating that the occupant is extracting webbing faster relative to the seat than a predetermined amount or the vehicle inertia sensing locking device is activated due to vehicle inclination, road induced vibrations etc. In a routine locking event, the profile head <NUM> is locked to the retractor frame <NUM> via a primary locking mechanism <NUM> until the retractor assembly <NUM> is reset. For example, the primary locking mechanism <NUM> may include locking teeth <NUM> that, during a locking event, engage with a receiving surface <NUM> of the profile head <NUM> and lock the profile head <NUM> with respect to the frame <NUM>. As a result, the spool assembly <NUM> may become locked with respect to the frame <NUM> via two main types of connections. For example, on one hand, the spool assembly <NUM> is locked with respect to the frame <NUM> via the fixed connection of the profile head <NUM> with the coupler end <NUM>, the fixed connection of the coupler end <NUM> with the torsion bar first end <NUM>, and the fixed connection of the torsion bar second end <NUM> and the spool element <NUM>. On the other hand, the spool assembly <NUM> is also locked with respect to the frame <NUM> via frictional forces such as press-fit engagement or other abutting engagement between the abutting surfaces 14a and 22a of the spool element <NUM> and the profile head <NUM>, respectively. When the spool assembly <NUM> is locked with respect to the frame <NUM>, the vehicle occupant's momentum or other forces may create seatbelt load forces in the direction <NUM>. However, during routine locking events, these seatbelt load forces are typically low enough such that the abutting surfaces 14a and 22a remain engaged without rotational, relative slippage between each other.

After a routine locking event, the spool assembly <NUM> typically or often remains locked with respect to the frame <NUM> until the retractor assembly <NUM> is reset, such as by the occupant allowing the seat belt webbing <NUM> to retract a predetermined distance and/or by unbuckling (when vehicle conditions safely allow) and allowing the retractor spring <NUM> to return the seat belt webbing <NUM> to the its retracted position. In this type of routine locking event, the pretensioner device <NUM> is not activated.

In another type of locking event, a collision condition locking event, the associated vehicle may undergo inertial loads or webbing extraction speeds outside prescribed limits, thereby indicating a vehicle crash or a potential vehicle crash. The associated vehicle and/or components of the retractor assembly <NUM> may be able to distinguish a routine locking event and a collision condition locking event via a number of mechanical, electrical, or other components, sensors, or systems. For example, the associated vehicle and/or components of the retractor assembly <NUM> may include an inertia sensitive locking system that detects inertia changes to the vehicle and/or components of the retractor assembly <NUM>. As a more specific example, the associated vehicle may include vehicle-mounted collision sensor <NUM> (<FIG>) that detect when the vehicle decelerates with a force equal to a predetermined amount, such as a force that generally corresponds to moderate to severe crashes.

During a collision condition locking event, the retractor assembly <NUM> typically operates generally similarly as it does during a routine locking event, with five main potential differences: (<NUM>) activation of the pretensioner, (<NUM>) rotational slippage between the abutting surfaces 14a and 22a of the spool element <NUM> and the profile head <NUM>, (<NUM>) deformation of the torsion bar <NUM>, (<NUM>) engagement of the spool rotation limiter <NUM>, and (<NUM>) engagement of the auxiliary locking mechanism <NUM>.

Regarding the first potential characteristic of a collision condition, in the event that a collision condition is detected, the pretensioner device <NUM> may be activated by sending a firing signal to an associated gas generator, thereby retracting a length of seat belt webbing <NUM> and tightening the seat belt against the vehicle occupant. The rotopretensioner may include a mechanism to lock the profile head <NUM> after undergoing pretensioning rotation.

In addition to such pretensioner locking, or independent of it, profile head <NUM> is locked in response to inertial loadings acting on the vehicle. For example, the primary locking mechanism <NUM> locking teeth <NUM> engage with the profile head <NUM> receiving surface <NUM> and lock the profile head <NUM> with respect to the frame <NUM>. As a result, the spool assembly <NUM> is locked with respect to the frame <NUM> via the fixed connection of the profile head <NUM> with the coupler end <NUM>, the fixed connection of the coupler end <NUM> with the torsion bar first end <NUM>, and the fixed connection of the torsion bar second end <NUM> and the spool element <NUM>. When the spool assembly <NUM> is locked with respect to the frame <NUM>, the vehicle occupant's momentum or other restraint forces may create seatbelt load forces in the direction <NUM>. The primary locking mechanism may also utilize the tread head (not shown) and/or pawls (not shown) for locking the profile head <NUM> to the retractor frame <NUM>. A tread head and pawls are well known in the art.

Regarding the second and third potential characteristics of a collision condition, the forces associated with the collision condition locking event may allow relative rotation between the abutting surfaces 14a and 22a of the profile head <NUM> and the spool element <NUM>. As a result, most or all of the restraint forces acting in the direction <NUM> act upon the torsion bar <NUM>, potentially causing deflection and/or deformation of the same. As discussed above, one end <NUM> of the torsion bar <NUM> is locked to the retractor frame <NUM> (via the profile head <NUM> and the coupler end <NUM>) while the other end <NUM> is coupled with the spool element <NUM>. The torsion bar <NUM> section between the attachment points (<NUM>, <NUM>) undergoes elastic and plastic torsional deflection, enabling torsion controlled, relative rotation between the spool element <NUM> and the retractor frame <NUM>. In other words, torsion bar <NUM> may undergo elastic (initially) and plastic torsional deformation, thereby allowing controlled extraction (protraction) of the belt webbing <NUM> while limiting belt loads. The force flow in such conditions may be from the seat belt webbing <NUM>, to spool element <NUM>, to torsion bar <NUM>, to the coupler end <NUM>, to the profile head <NUM>, to the primary locking mechanism <NUM>, to the frame <NUM>. The characteristics of torsion bar <NUM> are designed to provide predetermined load limiting characteristics. Several turns (full or partial) of relative rotation between torsion bar heads <NUM> and <NUM> may occur. The load limiting characteristics may be beneficial to limit forces from the seat belt webbing <NUM> acting on the vehicle occupant.

Regarding the fourth potential characteristic of a collision condition, the spool rotation limiter shown in <FIG> limits the spool rotation during a collision condition. For example, although it may be desirable for the torsion bar <NUM> to act as a load limiter, it may also be desirable to limit the seat belt webbing <NUM> extraction. As a more specific example, it may be desirable to limit the seat belt webbing <NUM> extraction after a predetermined number of relative rotations between torsion bar heads <NUM> and <NUM>. For example, referring to <FIG>, as the torsion bar <NUM> undergoes torsional deformation, the threaded nut <NUM> travels along the threaded portion <NUM> of the coupler end <NUM> towards the profile head wall <NUM>. After a certain number of rotations, determined by the thread pitch and the length of the threaded portion, the threaded nut <NUM> engages the profile head wall <NUM> and locks or substantially locks the spool element <NUM> and the profile head <NUM>, thereby preventing further rotation of the torsion bar <NUM>.

Regarding the fifth potential characteristic of a collision condition, the auxiliary locking mechanism <NUM> shown in <FIG> selectively locks the spool element <NUM> with respect to the retractor frame <NUM> upon the predetermined restraint load acting on the spool. For example, the auxiliary locking mechanism <NUM> shown in <FIG> includes a plurality of auxiliary locking teeth <NUM> defining a portion of the framewall 19a that selectively engage the auxiliary locking surface <NUM> defining a portion of the spool element <NUM>. The auxiliary locking mechanism <NUM> shown in <FIG> also includes the deformable bearing <NUM> positioned between the auxiliary locking surface <NUM> and the auxiliary locking teeth <NUM> to prevent engagement while the deformable bearing <NUM> is intact (i.e., before the predetermined restraint load). In other words, when the deformable bearing <NUM> remains intact and in position, it prevents contact between the auxiliary locking surface <NUM> of the spool element <NUM> and the auxiliary locking teeth <NUM>, thereby allowing the spool element <NUM> to rotate within bearing surface <NUM> without the auxiliary locking teeth <NUM> engaging or directly contacting the spool element <NUM>. However, upon the predetermined restraint load, the auxiliary locking teeth <NUM> break, deform, or displace the deformable bearing <NUM> and directly engage the auxiliary locking surface <NUM>.

The auxiliary locking mechanism <NUM> may be advantageous for a variety of reasons. For example, although it may be desirable for the torsion bar <NUM> to act as a load limiter, it may also be desirable to define an outer limit of seat belt webbing <NUM> extraction permitted during a crash event. As another example, the auxiliary locking mechanism <NUM> may provide increased retractor assembly <NUM> strength during a collision condition by providing an additional point of contact between the spool element <NUM> and the frame <NUM> and by providing a locking point on the opposite side of the seat belt webbing <NUM> than the primary locking mechanism <NUM>.

Upon reaching the predetermined restraint load, forces in the direction <NUM> may cause the spool element <NUM> and/or the torsion bar <NUM> to be radially displaced such that the auxiliary locking surface <NUM> of the spool element <NUM> presses upwardly on the deformable bearing <NUM>, into the auxiliary locking teeth <NUM>, with forces sufficient to break or displace or deform the deformable bearing <NUM> and to permit direct contact between the auxiliary locking surface <NUM> of the spool element <NUM> and the auxiliary locking teeth <NUM>. Upon contact between the auxiliary locking surface <NUM> and the auxiliary locking teeth <NUM>, the spool element <NUM> becomes substantially or completely locked to the frame wall 19a and substantially or completely prevents rotation of the spool element <NUM>. For example, the relatively sharp auxiliary locking teeth <NUM>, coupled with the collision forces in the direction <NUM>, cause the auxiliary locking teeth <NUM> to dig into the auxiliary locking surface <NUM> and substantially or completely prevent further seat belt webbing <NUM> extraction.

<FIG> shows a view of the frame sidewall 19a taken along line <NUM>--<NUM> in <FIG>, with portions of the torsion spring cap <NUM> and the retractor spring <NUM> visible through an opening <NUM> in the frame sidewall 19a. For illustrative purposes, the deformable bearing <NUM> and the spool element <NUM> are not shown in <FIG>.

<FIG> shows a view of the frame sidewall 19a taken along line <NUM>--<NUM> in <FIG>, with the auxiliary locking surface <NUM> of the spool element <NUM> extending through the opening <NUM> in the frame sidewall 19a and the deformable bearing <NUM> positioned between the auxiliary locking surface <NUM> and the auxiliary locking teeth <NUM>. <FIG> shows the retraction teeth <NUM> that engage with the retraction spring <NUM> (<FIG>, <FIG>) to retract slack from the seat belt webbing <NUM>. For example, as shown in <FIG>, the retraction spring <NUM> includes a bent end <NUM> for selectively engaging any one of the retraction teeth <NUM> (<FIG>).

Many different design parameters have the ability to affect the conditions in which the auxiliary locking mechanism <NUM> is engaged. For example, the thickness, material properties, surface smoothness and polish, manufacturing techniques, and other design parameters of the deformable bearing <NUM> may affect the conditions under which the auxiliary locking teeth <NUM> are able to directly engage the auxiliary locking surface, i.e. bearing <NUM>. As another example, the size, shape, sharpness, and material properties of the auxiliary locking teeth <NUM> may affect: (<NUM>) the collision forces and other conditions under which the deformable bearing <NUM> is caused to break and/or deform; (<NUM>) the time elapsed and the seatbelt webbing paid-out between the moment of direct contact between the auxiliary locking teeth <NUM> and the auxiliary locking surface <NUM> and the moment when the frame <NUM> and the spool element <NUM> are substantially or completely locked via the auxiliary locking mechanism <NUM>; (<NUM>) the extent to which metal is removed from or deformed on the auxiliary locking surface <NUM> when the auxiliary locking mechanism <NUM> is engaged; (<NUM>) the mechanism for unlocking or releasing the retractor assembly <NUM> after engagement of the auxiliary locking mechanism <NUM>. As yet another example, the material properties, surface smoothness and polish, manufacturing techniques, and other design parameters for the bearing surface are able to affect at least performance variables (<NUM>), (<NUM>), and (<NUM>) in the prior sentence.

<FIG> shows four additional embodiments of deformable bearings that are suitable with the auxiliary locking mechanism <NUM>. For example the second deformable bearing <NUM> is similar to the deformable bearing <NUM> shown in <FIG> but it has a sidewall <NUM> to keep the deformable bearing <NUM> in position between the frame <NUM> and the auxiliary locking surface <NUM> (not shown in <FIG>). During engagement of the auxiliary locking mechanism <NUM>, the sidewall <NUM> may remain intact even if the bearing surface <NUM> of the deformable bearing <NUM> becomes deformed or broken.

As another example in <FIG>, the third deformable bearing <NUM> includes two sidewalls <NUM>, <NUM> to keep the deformable bearing <NUM> in position between the frame <NUM> and the auxiliary locking surface <NUM> (not shown in <FIG>). More specifically, each sidewall <NUM>, <NUM> is positioned on opposite walls of the frame wall 19a. During engagement of the auxiliary locking mechanism <NUM>, the sidewalls <NUM>, <NUM> may remain intact even if the bearing surface <NUM> of the deformable bearing <NUM> becomes deformed or broken. The third deformable bearing <NUM> may also include slits <NUM> that help facilitate engagement of the auxiliary locking mechanism <NUM> under collision conditions. More specifically, under certain collision conditions, the auxiliary locking teeth <NUM> are able to break through the slits <NUM> to promote engagement between the auxiliary locking teeth <NUM> and the auxiliary locking surface <NUM> because the slits <NUM> may act as a starting point for deformation or breakage of the bearing surface <NUM>. The slits <NUM> are typically thinner than the thickness of the auxiliary locking teeth <NUM> to reduce the likelihood that the auxiliary locking teeth <NUM> extend through the bearing surface <NUM> during non-collision conditions.

As another example in <FIG>, the fourth deformable bearing <NUM> includes two sidewalls <NUM>, <NUM> to keep the deformable bearing <NUM> in position between the frame <NUM> and the auxiliary locking surface <NUM> (not shown in <FIG>). The fourth deformable bearing <NUM> may also include indentations <NUM> that help facilitate engagement of the auxiliary locking mechanism <NUM> under collision conditions. More specifically, the indentations <NUM> do not extend through the entire thickness of the bearing surface <NUM>, unlike the slits <NUM> in the third deformable bearing <NUM>, but they still affect the conditions under which the auxiliary locking teeth <NUM> are able to break through the bearing surface <NUM>.

As another example in <FIG>, the fifth deformable bearing <NUM> includes a sidewall <NUM> to keep the deformable bearing <NUM> in position between the frame <NUM> and the auxiliary locking surface <NUM> (not shown in <FIG>). The fifth deformable bearing <NUM> may also include teeth covers <NUM> that correspond to the shapes and sizes of the auxiliary locking teeth <NUM>. For example, each of the eight teeth covers <NUM> corresponds to a surface defining one of the eight teeth <NUM> such that when the fifth deformable bearing <NUM> is in position the teeth <NUM> and teeth covers <NUM> cooperate to define a relatively smooth surface around the opening <NUM>. Upon engagement of the auxiliary locking mechanism <NUM>, the teeth covers <NUM> are each likely deformed or broken away from the sidewall <NUM>.

It is notable that one or more of the deformable bearings (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) may be used in conjunction with each other. For example, the deformable bearing <NUM> may be used together with the fifth deformable bearing <NUM> such that the deformable bearing <NUM> creates a smooth, uninterrupted surface for engagement with auxiliary locking surface <NUM> and such that the fifth deformable bearing <NUM> is able to reduce or prevent pressure points between the moving components.

<FIG> show various embodiments of frame teeth <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>. The frame teeth shown in the Figures herein are each designed to minimize the engagement between the frame teeth and the spool auxiliary locking surface <NUM> until the auxiliary locking mechanism <NUM> is engaged. As discussed above, the size, shape, sharpness, and material properties of the auxiliary locking teeth <NUM> are able to affect many performance variables. For example, frame teeth <NUM> have a smaller profile than the auxiliary locking teeth <NUM> shown in <FIG>, thereby potentially leading to an increased time elapsed and the seatbelt webbing paid-out between the moment of direct contact between the frame teeth <NUM> and the auxiliary locking surface <NUM> and the moment when the frame <NUM> and the spool element <NUM> are substantially or completely locked via the auxiliary locking mechanism <NUM>. As another example, frame teeth <NUM> are angled away from the direction of rotation, unlike the auxiliary locking teeth <NUM>, thereby also potentially leading to an increased time elapsed and seatbelt webbing paid-out and also potentially making it easier to unlock or release the retractor assembly <NUM> after engagement of the auxiliary locking mechanism <NUM> because the frame teeth <NUM> may take longer to dig into the material of the auxiliary locking surface <NUM>. As yet another example, frame teeth <NUM> each have a top edge that is not perpendicular to the frame sidewall 19a, thereby potentially leading to a decreased time elapsed and seatbelt webbing paid-out the fire and potentially increasing the extent to which metal is removed from or deformed on the auxiliary locking surface <NUM> when the auxiliary locking mechanism <NUM> is engaged. As another example, the frame teeth <NUM>, <NUM>, <NUM>, <NUM> may have irregular or varying teeth profiles.

<FIG> schematically illustrates a seatbelt assembly <NUM> utilized in a vehicle <NUM>, such as a motor vehicle. The vehicle <NUM> includes a seat <NUM> mounted to the vehicle that is able to support a occupant <NUM>. The seatbelt assembly <NUM> includes the retractor assembly <NUM> mounted to the vehicle <NUM>, the pretensioner assembly <NUM> mounted to the retractor assembly <NUM> or the vehicle <NUM>, the seatbelt webbing <NUM> stored on the on the spool of the retractor assembly <NUM>, a buckle <NUM> having a female portion mounted to the seat <NUM> or the vehicle <NUM> and able to receive the buckle male portion coupled with one end of the seatbelt webbing <NUM>, and an anchor <NUM> mounted to the vehicle <NUM> and supporting the seatbelt webbing <NUM> near the shoulder area of the occupant <NUM>. The vehicle <NUM> illustrated in <FIG> also includes the collision sensor <NUM> that detects inertia changes to the vehicle <NUM>.

Claim 1:
A vehicle seat belt retractor (<NUM>) including:
a spool (<NUM>) rotatable with respect to a retractor frame (<NUM>), the spool (<NUM>) storing a seat belt webbing (<NUM>) wrapped thereon;
a primary locking mechanism (<NUM>) for selectively locking the spool (<NUM>) with respect to the retractor frame (<NUM>) to provide vehicle occupant restraint;
an auxiliary locking mechanism (<NUM>) for selectively locking the spool (<NUM>) with respect to the retractor frame (<NUM>) upon a predetermined restraint load acting on the spool (<NUM>), wherein
the auxiliary locking mechanism (<NUM>) includes at least one auxiliary locking tooth and an auxiliary locking surface (<NUM>) to restrain relative movement between the retractor frame (<NUM>) and the spool (<NUM>), wherein
the at least one auxiliary locking tooth defines a portion of the retractor frame (<NUM>) and the auxiliary locking surface (<NUM>) defines a portion of the spool (<NUM>), wherein
the spool (<NUM>) undergoes radial displacement upon the predetermined restraint load acting on the spool (<NUM>)
characterized by, a deformable bearing (<NUM>,<NUM>,<NUM>,<NUM>,<NUM>) at least partially positioned between the at least one auxiliary locking tooth and the auxiliary locking surface (<NUM>) to substantially prevent engagement between the at least one auxiliary locking tooth and the auxiliary locking surface (<NUM>) until the predetermined restraint load acting on the spool (<NUM>), wherein the deformable bearing (<NUM>,<NUM>,<NUM>,<NUM>,<NUM>) further includes at least one sidewall (<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>) substantially perpendicular to the bearing surface and configured to abut a wall (19b) of the retractor frame (<NUM>).