GB2453028A

GB2453028A - Strap retractor having an opening that resists twisting of the restraint strap

Info

Publication number: GB2453028A
Application number: GB0816651A
Authority: GB
Inventors: Roger Dick; Joe Esteireiro; Jean-Marc Girardin
Original assignee: Valeda Co LLC
Current assignee: Valeda Co LLC
Priority date: 2007-09-21
Filing date: 2008-09-11
Publication date: 2009-03-25
Also published as: GB0816651D0; DE102008047876A1; US20090078811A1

Abstract

A strap retractor comprises a housing 10, retractor spool 22, a restraint strap 14 wound on the retractor spool and an opening 40 having a device to resist twisting of the restraint strap. The opening may be equal to between two and eight times the thickness of a strap. The housing may be a retractor cover or a barrier hosing. The opening may be provided with at least one guide surface 50, 60, 70, 80 having at least one slope. The guide surfaces can be integrally formed with the retractor housing or can be provided by an insert piece which attaches to the housing. The guide surface may be disposed along an upper wall of the opening and be curvilinear and outwardly diverging. More specifically, the guide surface may have slopes that vary along its length whereby the guide surface is approximately vertical near a leading edge of the guide surface and is approximately horizontal near a trailing edge.

Description

TITLE

Anti-Twist Device.

FIELD OF THE INVENTIONS

The embodiments described and claimed herein relate generally to wheelchair securement devices for vehicles. More specifically, one embodiment described herein relates to a retractor cover, which includes features to prevent twisted webbing or restraint strap from passing into the retractor housing. Another embodiment relates to a retrofit insert for a retractor cover, which includes similar anti-twist features. Yet another embodiment relates to an anti-twist guide slot, or retrofit insert for a slot, which could be used in a location remote from the retractor.

BACKGROUND OF THE INVENTIONS

Retractors are utilized in a number of different applications, such as safety harnesses, automobile seatbelt systems, and wheelchair securement systems for vehicles. The particular embodiments disclosed herein are primarily adapted for use in wheelchair securement systems for restraining both the wheelchair and the wheelchair passenger, although it is envisioned that the features shown and described herein could be utilized in an equally effective manner in other applications.

It is well known that retractors can be installed in a number of different configurations.

In a most simple application, four retractors can be mounted to a vehicle's floor or near thereby, one for securing each corner of a wheelchair. For examples of prior art retractors, see Q'Straint's QRT retractors at www.qstraint.com and Sure-Lok's Retraktor Series System at www.sure lok.com. Since floor-mounted retractors can present serious tripping hazards for vehicle passengers, manufacturers have developed various apparatus for reducing or minimizing the tripping hazard. For example, as described in U.S. Patent Application No. 11/776223, which is

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incorporated herein by reference, Q'Straint has developed a retractable wheelchair anchor onto which two retractors can be mounted. Q'Straint's wheelchair anchor includes a foot-operated telescoping arm, which retracts into a non-use position to present a lesser tripping hazard than floor-mounted retractors. See also American Seating's Advanced Restraint Module ("A.R.M.") at www.americanseating.com. Q'Straint has also developed a forward facing barrier system as disclosed in U.S. Patent Application Serial No. 11/847435, which is incorporated herein by reference. Q'Straint's forward facing barrier includes a housing for concealing internally mounted retractors, whereby the webbing from each retractor passes through a corresponding slot in the barrier housing.

In wheelchair securement applications, retractors often include up to several feet of webbing. At its proximal end, the webbing is attached to a spring loaded spool which is disposed within a cover or housing. At its free end, the webbing is typically attached to an anchor (such as an S-hook or i-hook), which is adapted to engage with a structural member of a wheelchair, thereby securing the wheelchair. Alternatively, the webbing can be adapted for use as a lap or shoulder belt for the wheelchair passenger and, for such applications, can include some sort of a connector, such as a male, female, or pin connector.

When used in exposed applications -for example, if the retractors are floor-mounted or mounted onto a retractable wheelchair anchor -the retractor will usually include a metal or plastic cover for housing and protecting the working components of the retractor. When used in non-exposed applications -such as when mounted internal to the barrier housing -use of a zinc cover is prohibitively expensive. For this reason, manufacturers often will not use a separate cover (or housing) for the retractor and will instead rely upon the barrier housing to protect the retractor. Alternatively, manufacturers may use an inexpensive cover, such as a plastic one.

While all current wheelchair retractors are vulnerable to twists in the webbing, self-locking retractors are particularly so since they have openings which are relatively large, having an effective height which is generally more than ten (10) times the thickness of the webbing itself. The openings are large since self-locking retractors utilize a double stitched portion of webbing, which must be passed through the opening to enable the self-locking feature. The double stitched portion of webbing is simply the free end of the webbing that is looped through the anchor, folded back over itself, and stitched together. When the webbing is fully retracted, a length of double stitched webbing is wound on the retractor spool such that it triggers a locking bar. In this configuration, the retractor is "unlocked," such that the webbing can be freely pulled out of the retractor. When the double stitched portion of webbing is pulled out of the retractor, the locking bar is released, but does not filly engage (i.e., to prevent further extension of the webbing) until the attendant stops pulling on the webbing and allows the self-tensioning feature of the retractor to retract a small amount of webbing.

In typical use of any of the above described wheelchair securement systems, an attendant (or vehicle operator) grasps and pulls the anchor (or lap and shoulder belt connectors), thereby drawing webbing out from the retractor spool, and attaches the anchor to a structural member of the wheelchair (or attaches the lap and shoulder belts together). Often times, the attendant will introduce twists into the webbing which may not be "undone" when the anchor is released from the wheelchair (or the lap belt is released). The twist may pass through the housing and become wound onto the retractor spool (note that, for the above described wheelchair securement systems, the term housing refers to either or both the retractor cover and barrier housing). Once the twist is wound onto the retractor spool, the twist can interfere with proper functioning of the retractor such that the efforts required to pull the webbing from the retractor are increased. )

Moreover, the twist may cause the webbing to overlap the gears, which in turn causes accelerated wear of the webbing and could possibly jam the retractor. Sometimes, it may be impossible to extend the webbing without disassembling the retractor or the barrier In such cases, the retractor will not work and, hence, the securement system will be unusable.

Wheelchair securement system manufacturers, being aware of and until now being unable to solve these problems, instruct their customers to regularly inspect for twists in the webbing.

Ideally, a vehicle operator will inspect the webbing for twists every time before secunng a wheelchair. In the case of mass transit vehicles, this additional step increases the dwell time at stops and increases the risk of the operator suffering from a back injury.

SUMMARY OF THE INVENTIONS

The embodiments described and claimed herein at least partially reduce the risk of twisting.

As discussed briefly above, it is believed that the configuration (i.e. size and or shape) of the prior art openings (or guide slots) allow the twists to pass through unimpeded. Therefore, the openings shown and described herein incorporate some combination of features which smooth out the webbing as it passes through the opening and/or urge the webbing into alignment with the opening.

hi this maimer, the embodiments described, shown, and claimed herein reduce the chances that the webbing will fold over into a double thickness and become wound onto the retractor spool.

For example, one embodiment described herein is a housing for a retractor. The housing, in turn, defines an interior space in which the working components of the retractor are disposed and has an opening which is adapted for passing webbing therethrough. The opening in the housing has at least one guide surface which is integrally formed therein. The guide surface is configured to guide the movement of the webbing and thereby resist the passing of twists in the webbing through the opening. More specifically, the guide surface has a leading edge being disposed generally near

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an outside the housing, a trailing edge, and at least one slope therebetween, wherein the at least one slope causes the leading edge to diverge from the opening. In another embodiment, the housing for the refractor is a retractor cover. In yet another embodiment, the retractor is internally mounted in a barrier, whereby the housing for the retractor is a barrier housing.

Another embodiment described herein is a retrofit insert piece or webbing guide which is adapted to attach to a housing for a retractor and which provides at least one guide surface for the opening in the housing. Like the guide surface of the first embodiment, the guide surface of the second embodiment serves to resist a twist in the webbing from passing through the opening. More specifically, at least a portion of the guide surface is aligned in non-parallel relation to the axis of the opening, whereby the portion the guide surface is outwardiy diverging. In another embodiment, the housing for the retractor is a retractor cover, hi yet another embodiment, the retractor is internally mounted in a barrier, whereby the housing for the retractor is a barrier housing.

Other embodiments, which include some combination of the features discussed above and below and other features which are known or unknown in the art, are contemplated as falling within the claims even if such embodiments are not specifically identified or discussed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, objects, and advantages of the embodiments described and claimed herein will become better understood upon consideration of the following detailed description, appended claims, and accompanying drawings where: Figure 1 is a perspective view of a first embodiment of a retractor housing, which includes integrally formed guide surfaces at the opening of the housing; Figure 2 is a first perspective, exploded view of the same; Figure 3 is a second perspective, exploded view of the same; Figure 4 is a cross sectional view of the same; Figure 5 is a top view of a lower member of the retractor housing; Figure 6 is a bottom view of an upper member of the retractor housing; Figure 7 is a perspective view of a second embodiment of a retractor, which includes a retrofit webbing guide; Figure 8 is a perspective view of the retrofit webbing guide; Figure 9 is a front view of the same; Figure 10 is a bottom view of the same; Figure 11 is a cross sectional view of the same; Figure 12 is a perspective view of the second embodiment of the retractor, which the retrofit webbing guide partially inserted into the opening in the retractor housing; Figure 13 is a cross-sectional view of the first embodiment of the retractor housing, showing the relative location of the upper guide surface with the internal mechanisms of the retractor; Figure 14 is a cross-sectional view of the second embodiment of the retractor housing, showing the relative location of the retrofit insert with the internal mechanisms of the retractor; Figure 15 is a forward facing barrier which includes anti-twist guide slots for wheelchair securement and lap and shoulder belt retractors; Figure 16 is a close-up view of the same showing the anti-twist guide slots for the wheelchair securement and lap belt retractors; Figure 17 is a close-up view of the same showing the anti-twist guide slots for the shoulder belt retractor; and, Figure 18 is a perspective view of a second embodiment of a retrofit webbing guide.

It should be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views, in certain instances, details which are not necessary for an understanding of the embodiments described and claimed herein or which render other details difficult to perceive may have been omitted. It should be understood, of course, that the inventions described herein are not necessarily limited to the particular embodiments illustrated.

Indeed, it is expected that persons of ordinary skill in the art may devise a number of alternative configurations that are similar and equivalent to the embodiments shown and described herein without departing from the spirit and scope of the claims.

Like reference numerals will be used to refer to like or similar parts from Figure to Figure in the following detailed description of the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Various embodiments of an anti-twist slot or opening for passing webbing therethrough are described and shown herein which incorporate some combination of features which substantially reduce the chance that twisted webbing will become wound onto a retractor spool and therefore interfere with the functionality of a retractor. Some of the features of the openings which make this possible relate to the height of the opening as compared to the thickness of the webbing, the length of the innermost guide surface on the upper wall (or various other walls depending upon orientation), the proximity of the innermost guide surface on the upper wall (or various other walls depending upon orientation) to the retractor spool, the aspect ratios of the opening, and/or the contours of the opening side walls. Although the embodiments depicted herein include openings having specific aspect ratios and specific contours, it is in no way intended that the inventions be limited to those specific values or those specific combinations of aspect ratios and contours. The specific dimensions recited herein are for example purposes only and apply only to the specific embodiments shown in the figures. The dimensions are not intended to be limiting upon the claims except to the extent that specific dimensions are explicitly recited therein Indeed, the dimensions could vary widely (even outside the specific ranges provided herein) depending on various factors, including the type of application, the length and thickness of the webbing, etc. Referring first to Figures 1-6 and 13, a first embodiment of a housing 10 for a retractor is depicted. The retractor housing 10 of the first embodiment is a retractor cover and comprises an upper member 20 and a lower member 30, which are adapted to engage and thereby form an enclosure. Although not all components are shown, the housing is intended to enclose and protect the various working components of the retractor, including a spring loaded spool mechanism 22, which in turn carries webbing 14. Although the housing 10 is comprised of two members 20, 30, it is contemplated that the housing 10 could be defined by more or less members.

The upper member 20 and lower member 30 merge to define an opening 40, through which the webbing is intended to pass. The opening 40 can be any shape (for example, such as oval or hexagonal), but as shown is generally quadrangular wherein the opening 40 is defined by four side walls 50, 60, 70, 80. The four sidewalls 50, 60, 70, 80 are guide surfaces and, as shown, are generally curvilinear and inwardly converge towards each other (or, in other words, outwardly diverge). Although all four sidewalls 50, 60, 70, 80 of the shown embodiment are configured as guide surfaces, it is contemplated that less than all of the side walls could be configured as such. in fact, configuring the opening with a single guide surface may be sufficient.

For purposes of this description, it is assumed that the retractor housing 10 is horizontally oriented. Therefore, the first sidewall 50 is referred to herein as an upper sidewall 50, the second sidewall 60 is referred to herein as a lower sidewall 60, the third sidewall 70 is referred to herein as a left sidewall, and the fourth sidewall 80 is referred to herein as a right sidewall. However, since it is contemplated that the retractor housing 10 could be oriented vertically or in an inclined configuration, the use of the terms upper and lower are used for purposes of description and not for purposes of defining the relative location of these walls when the retractor housing is installed.

The upper sidewall 50, as shown, includes several guide surfaces or portions and is both curvilinear and inwardly converging, although it is contemplated that the upper sidewall 50 could be entirely linear, or include linear portions. As best shown in Figure 4, the upper sidewall 50 has slopes that vary along its length (i.e., in the direction of travel of the webbing) and, as shown, has an inner portion 52 and an outer portion 54. Starting from an inner extent of the inner portion 52 and moving outwardly, the inner portion 52 is approximately linear and parallel with the axis of the opening and/or the general plane along which the webbing travels, although it is contemplated that the inner portion 52 could be curvilinear and oriented an angle to the axis of the opening. The intersection 56 between the inner portion 52 and the outer portion 54 is characterized by a substantial increase in slope along its length. In that respect, the upper sidewall 50 begins to diverge from the lower side wall 60 near or at the intersection 56. The intersection 56 has an approximate radius of 0.20", although radii in the range of approximately 0.1" to 0. 3" would also be sufficient. The upper sidewall 50 continues to diverge from the lower sidewall along the length of the outer portion 54, although to a much greater extent than at the intersection 56. The outer portion 54 is marked by a gradual increase in slope and, at an outer extent, approaches approximately vertical. The outer portion 54 has a radius of approximately 0.30" near its midpoint, although a radius of approximately 0.20" to 0. 40" would also be sufficient.

For a horizontally oriented retractor, it has been found that the upper sidewall 50 contributes more significantly to the anti-twist capability of the retractor housing, than do the other sidewalls 60, 70, 80. It has also been found that some features of the upper waIl 50 contribute more significantly to the anti-twist capability of the retractor. For example, it is believed that better results can be obtained by maximizing the length of the inner portion of the upper sidewall 50 and positioning the inner extent of the inner portion 52 as near as possible to the spool mechanism or the webbing which is wound thereon. In fact, for a horizontally oriented retractor, it is believed that satisfactory results could be obtained by merely configuring the upper wall as a planar surface which extends a distance from an outside surface of the retractor housing into the opening.

Like the upper sidewall 50, the lower sidewall 60, as shown, is both curvilinear and inwardly converging. As best shown in Figure 4, the lower sidewall 60 has slopes that vary along its length and, as shown, has an inner portion 62 and an outer portion 64. Starting from the inside of the housing 10 and moving outwardly, the inner portion 62 is substantially parallel with the axis of the opening and/or the general plane along which the webbing travels. The intersection 66 between the inner portion 62 and the outer portion 64 is characterized by a substantial decrease in slope along its length. In that respect, the lower sidewall 60 begins to diverge from the upper side wall 56 near or at the intersection 66. The intersection has an approximate radius of 0.34", although a radius in the range of approximately 0.24" to 0.44" would also be sufficient. The lower sidewall 60 continues to diverge from the upper sidewall 50 along the length of the outer portion 64, although to a slightly greater extent than at the intersection 66. The outer portion 64 is marked by a gradual decrease in slope and, at an outer extent, passes through vertical.

The left and right sidewalls 70, 80 are essentially mirror images of each other. For that reason, only the left sidewall 70 is described in detail herein. As best shown in Figure 5, the left sidewall 70 (like both the upper and lower sidewalls 50, 60) is both curvilinear and inwardly converging. Moreover, the left sidewall 70 includes an inner portion 72 and an outer portion 74, which merge at an intersection 76. The length of the inner portion 72 is aligned substantially parallel with the direction of travel of the webbing and/or the axis of the opening, while the outer portion diverges away from the axis of the opening at an angle of approximately 32 degrees. It is contemplated, however, that the outer portion could be oriented at other angles, such as between approximately 30 degrees to 45 degrees. The intersection 56, as shown, has a radius of approximately 0.20", although a radius in the range of 0.10" to 0.30" would also be sufficient.

The outer portions 54, 64, 74, 84 of the sidewalls 50, 60, 70, 80 can be characterized as smoothing surfaces. Since these portions 54, 64, 74, 84 of the sidewalls are marked by gradual changes in slope and/or generally diverge from the axis of the opening, it is believed that these surfaces exert only low to moderate untwisting forces on the webbing. The inner portions 52, 62, 72, 82 and/or the intersections 56, 66, 76, 86 of the sidewalls 50, 60, 70, 80 can be characterized as urging surfaces, as they are marked by a greater change in slope and/or are substantially parallel with the axis of the opening. It is believed that the urging surfaces are more capable of exerting greater untwisting forces on the webbing. When both are present, the smoothing and urging surfaces cooperatively work to prevent twisted webbing from passing through the opening 40.

In additional or in the alternative to the various contours of the sidewalls 50, 60, 70, 80, it is believed that the aspect ratios of the opening 40 contribute to the untwisting capabilities of the retractor housing 10. The opening 40 can be characterized as having major dimensions of Wi x H1 and minor (or effective) dimensions of W2 x H2. At some point along the depth D of the opening 40, there is an intermediate plane where the opening 40 has intermediate dimensions which are approximately equal to or slightly greater than the minor dimensions. The intermediate plane occurs at a depth D1 from the outer extent of the opening 40. The location of the intermediate plane approximately corresponds with the location of the intersections 56, 66, 76, 86, at the point at which the opening 40 begins to substantially diverge outwardly. In the shown embodiment, W1 is approximately equal to 2.3", W2 is approximately equal to 1.96", H1 is approximately equal to 1", H2 is approximately equal to 0.24", D is approximately equal to 0.40", and D1 is approximately equal to 0.20". It must be kept in mind, as discussed in more detailed above, that the dimensions recited herein can vary substantially without affecting the anti-twist capabilities.

It is believed that the extent to which the opening is capable of inducing smoothing and urging actions on the webbing can be measured by various aspect ratios, including the major to minor height and width ratios and various other ratios (which can be easily calculated from the dimensions provided above or scaled from the attached figures).

The major to minor height ratio:H, as shown, is approximately 4:1, although a major to minor height ratio of approximately 3:1 to 5:1 would also be sufficient. The major to minor width ratio W1:W2, as shown, is approximately 1.17:1, although a major to minor width ratio of approximately 1:1 to 1.7:1 would also be sufficient. As the height and width ratios approach 1, the opening is likely imparting more of an urging action than a smoothing action on the webbing.

In contrast, as the height and width ratios approach infinity, the opening is likely imparting more of a smoothing action than an urging action. In addition or in alternative to providing the opening 40 with any combination of the features described above, conforming the opening 40 of the retractor housing 10 to satisfy at least some of these parameters will contribute to anti-twist capabilities of the opening.

It is further believed that the anti-twist capabilities of the shown embodiments are enhanced due to the dimensional relationship of the opening height with the webbing thickness.

For comparison purposes, the thickness of typical webbing (or restraint strap), is approximately 1.2 mm. When folded over into double thickness and stitched together, the webbing will have a thickness of around 2.4 to 2.5 mm. With H2 equal to 5.59 mm, it is understood that the effective height of the opening, being slightly greater than the thickness of double stitched webbing (about 2.2 times greater than a double stitched portion or about 4.7 times greater than single thickness webbing), allows a double stitched portion of webbing to pass into the opening. It has been found that by closely conforming the height of the opening with the maximum thickness of webbing in the manner described above (i.e., for the shown embodiments, the thickness of a double stitched portion), there is a reduced chance that an unintended folded over portion of webbing will enter the retractor. It is believed that satisfactory results can be obtained by reducing the effective height of the opening such that it is less than ten times the thickness of the webbing. It has been observed, however, that the ability of the opening to resist the passing of twists exponentially increases by decreasing the effective height of the opening, where the best results can be obtained with an opening that has an effective height which is approximately equal to the thickness of a double stitched portion of webbing (i.e., approximately two times the thickness of the webbing). Ideally, the opening will have an effective height which is between approximately two (2) to six (6) times the thickness of the webbing itself.

Referring now to Figure 7-12 and 14, a second embodiment of a retractor 110 is shown.

The second embodiment of the retractor 110 can be substantially similar to prior art retractors, in that it comprises a housing 112 for enclosing and protecting the working components of the retractor, including a spool mechanism 116, and having a quadrangular opening 140 through which webbing 114 is adapted to pass. Where the second embodiment of the retractor 110 differs from the prior art is its inclusion of a retrofit anti-twist insert (or member) 145, which modifies the size and shape of the opening 140 with the aim to reduce the chance that twisted webbing will pass into the retractor housing 112. Although the anti-twist insert 145 is designed to be easily installed by end-users as an after-market component to provide pre-existing retractor housings with anti-twist capability, other configurations are contemplated which may require a skilled technician for installation.

For practical reasons, the insert 145 is shaped like a "U" and, therefore, has three sections 155, 175, 185. This construction allows the insert piece 145 to be installed around the webbing, thereby negating the need to disassemble the retractor and feed the webbing through the insert piece. Although the convenience of a three sided retrofit piece 145 is recognized herein, it is by no means asserted that it would be impossible or prohibitively difficult to utilize a four-sided piece or that the claims herein do not cover such an embodiment. Indeed, it is contemplated that a four-sided retrofit piece could be made which would require the end-user (or maintenance personal) to disassemble the retractor 110 and feed the webbing 114 through the retrofit piece.

Alternatively, the retrofit piece could comprise two sections, one of which is installed on one side of the webbing 114 and the other of which is installed on the other side of the webbing 114. Yet another alternative embodiment is shown in Figure 18. The second embodiment of the retrofit piece 345 is four-sided, having four sidewalls 350, 360, 370, 380, each of which could inc lude a guide surface. One of the sides 380 includes a cut 385, through which the webbing can be inserted. Utilizing the elasticity of the retrofit piece 345, a gap can be formed at the cut 385 by grasping the piece 345 from opposite sides of the cut 385 and pulling in the directions indication by the arrows in Figure 18. When the piece 345 is manipulated in such a manner, the opposite side 370 acts as a hinge to allowing a gap to be formed at the cut 385, whereby the webbing can be slid into the opening of the retrofit piece 345.

Referring again to the embodiment shown in Figure 7-12 and 14, the first embodiment of the retrofit insert piece 145 includes at least one guide surface 150, which in the shown embodiment is present on the upper section 155. It is contemplated that, in combination or in the alternative, the side sections 175, 185 could include similar guide surfaces. In addition, for a four sided retrofit insert piece (not shown) one or more, or even all, sides could include guide surfaces. See, for example, the guide surfaces provided by the first embodiment of the retractor housing 10. It should be noted that the particular housing 112 disclosed in the figures includes an opening that is not sufficiently wide to include guide surfaces on the side sections 175, 185.

Inclusion of guide surfaces on the side sections 175, 185 would reduce the width of the opening to the point of buckling the webbing.

The guide surface 150 is shown as curvilinear and inwardly converging, although it is contemplated that the guide surface could be planar and/or discontinuous, just like the guide surfaces 50, 60, 70, 80 of the previous embodiment. As best shown in Figure 11, the guide surface 150 has slopes that vary along its length (i.e., along the direction of travel of the webbing) and, as shown, has an inner portion 152 and an outer portion 154. Starting from an inner extent of the inner portion 152 and moving outwardly, the inner portion 152 begins as nearly parallel with the direction of travel of the webbing (see Figure 14) and gradually increases in slope. In that respect, the upper guide surface 150 diverges from the lower wall of the opening 140. The intersection 156 between the inner portion 152 and the outer portion 154 is characterized by a more substantial increase in slope along its length. The intersection has an approximate radius of 0.14", although the radius could vary widely with similar results. The upper sidewall 150 continues to diverge from the lower wall of the opening 140 along the length of the outer portion 154, although to a much greater extent. The outer portion 154 is marked by a gradual increase in slope and, at an outer extent, approaches approximately vertical. The outer portion 154 has a radius of approximately.13" near its midpoint, although the radius could vary widely with similar results.

In addition or in the alternative to changing the contour of the opening 140, the insert piece 145 contributes to the untwisting capabilities of the retractor housing 112 by modifying the aspect ratios of the opening 140. Conforming the insert 145 to satisfy at least some of the parameters provided above for the first embodiment will contribute to anti-twist capabilities of the opening.

The insert piece 145 includes multiple locking grooves 151, 172, 174, 182, 184 which are adapted to engage with the periphery of the opening 140. In the shown embodiment, the locking groove 151, 172, 174, 182, 184 are essentially narrow channels which are adapted to receive the thin-wall construction of the retractor housing 112 which surrounds the opening 140. The first (or top) section 155 of the insert piece 145 includes one generally elongated locking groove 151 which is adapted to engage with the upper wall of the opening 140. Both the second and third (or right and left side) sections 175, 185 include two locking grooves 172, 174, 182, 184 which are adapted to engage with the side walls and lower wall of the opening 140. The locking grooves 151, 172, 174, 182, 184 are generally bounded by an outer lip 157, 177, 187 and inner lips 159, 179, 189. In the shown embodiment, the outer lip 157, 177, 187 continuously extends around the periphery of the insert 145 and has outer dimensions which exceed that of the opening 140. In that respect, the inside surface of the lip 157,177, 187 rests against the outside surface of the retractor housing 112 and thereby frames the opening 140. The inner lips 159, 179, 1 89 are discontinuous to reduce the force required to install the retrofit insert 145. However, it is contemplated that the outer lip 157, 177, 187 could be discontinuous andlor the inner lips 159, 179, 189 could be continuous.

As best shown by Figure 12, the insert piece 145 is configured to be installed, at least in part, by "snapping." First, the insert piece 145 is tilted such that the upper locking groove 151 engages with the upper wall of the opening 140. Then, the lower edge of the insert piece 145 is rotated into engagement with the lower wall of the opening 140. Moderate force may be required to snap the lower and side edges of the insert piece 145 into engagement with the opening. To reduce the required installation force, the inner lips 179, 189 have chamfered rear edges.

Although the insert component 145 is characterized as a retrofit piece, and it was initially intended that it be used with existing retractors to provide anti-twist capabilities, it is not necessary that the retrofit piece 145 be used solely with pre-existing retractors. Indeed, it is contemplated that the retrofit piece 145 could be used or simply modified for use with new and currently non-existing retractors. Alternatively, the anti-twist inserts 145 can be installed into pre-existing guide slots in barrier housings or other similar structures, to prevent twisted webbing from passing into the barrier housing and becoming wound onto a retractor spool.

Referring now to Figures 15-17, a third embodiment of a housing 210 for a retractor is shown. The housing 210 is a barrier-type housing, similar to that disclosed in U.S. Patent Application Serial No. 11/847435, which houses multiple, internally-mounted retractors for restraining a wheelchair and wheelchair passenger. Specifically, two retractors are provided for restraining a wheelchair from the rear side and three retractors are provided for restraining a wheelchair passenger (i.e., by providing lap and shoulder belts). The retractors include up to several feet of webbing, which pass through a plurality of anti-twist slots 220a, 220b, 230a, 230b, 240 in the housing, so that they may be accessible for use. Each of the slots 220a, 220b, 230a, 230b, 240 include one or more anti-twist guide surfaces which may be similar to those disclosed by the first and second embodiments. Specifically, the anti-twist lap belt slot 220a (which is similar, identical, or a mirror image of the anti-twist lap belt slot 220b) includes a left sidewall guide surface 222a, a right sidewall guide surface 224a, an upper sidewall guide surface 226a, and a lower sidewall guide surface 228a. The anti-twist rear wheelchair securement belt slot 230 (which is similar, identical, or a niirror image of the anti-twist slot 230b) includes a left sidewall guide surface 232a, a right sidewall guide surface 234a, an upper sidewall guide surface 236a, and a lower sidewall guide surface 238a. The anti-twist shoulder belt slot 240 is provided with an upper side wall guide surface 242, a lower sidewall guide surface 244, a left sidewall guide surface 226 and a right sidewall guide surface 248. The anti-twist guide surfaces for the barrier housing 210 can be provided with contours similar to any of the above described guide surfaces and/or can cooperate to provide the opening with any of the various aspect ratios defined above to reduce the chance of twisted webbing from passing through the slot.

Although the inventions described and claimed herein have been described in considerable detail with reference to certain embodiments, one skilled in the art will appreciate that the inventions described and claimed herein can be practiced by other than those embodiments, which have been presented for purposes of illustration and not of limitation.

Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

Claims

CLAIMS: 1. A device for reducing the chances that a twisted portion of a restraint strap will mterfere with the operation of a retractor comprising: a housing, a retractor spooi, and a restraint strap, the restraint strap being wound on the retractor spool and having a thickness; the housing defining an interior space in which a retractor spool is disposed and having an opening which is adapted for passing the strap therethrough; and, the opening having an effective height which is between approximately two and eight times the thickness of the restraint strap to allow a double stitched portion of the restraint strap to pass therethrough.
2. The device of claim 1, wherein the effective height is between approximately two and six times the thickness of the restraint strap.
3. The device of claim 1, wherein the housing is a retractor cover.
4. The device of claim 1, wherein the housing is a barrier housing.
5. The device of claim 1, wherein the opening is provided with at least one guide surface, the guide surface having at least one slope between a leading edge and a trailing edge, wherein the at least one slope causes the leading edge to diverge from an opposing sidewall.
6. The device of claim 5, wherein the at least one slope comprises at least a first slope near the leading edge and at least a second slope near the trailing edge, wherein the guide surface is aligned approximately perpendicular to an axis of the opening near the leading edge and is aligned approximately parallel to the axis of the opening near the trailing edge.
7. The device of claim 6, wherein the guide surface is curvilinear and includes a variable slope between the leading and trailing edges.
8. The device of claim I, wherein the opening includes a plurality of contoured guide surfaces, at least one of which is adapted to guide the movement of the lateral edges of the strap
9. The device of claim 1, wherein a guide surface for the opening is formed on a member which is attachable to the housing, the guide surface constricting a size of the opening to provide the opening with the effective height.
10. The device of claim 9, wherein the member includes at least one locking groove whereby the member can be engaged with the opening by snapping into place.
11. The device of claim 1, wherein the opening is generally quadrangular and includes four walls, onto one of which at least one guide surface is formed.
12. A device for reducing the chances that a twisted portion of a restraint strap will interfere with the operation of a retractor comprising: a housing, a retractor spooi, and a restraint strap, the restraint strap being wound on the retractor spool and having a thickness; the housing defining an interior space in which a retractor spool is disposed and having an opening which is adapted for passing the strap therethrough; the opening having at least one sidewall, with at least a portion of the sidewall having a guide surface, the guide surface being configured to guide the movement of the strap and thereby resist the passing of a twist in the strap through the opening and into the housing; and, the guide surface having a leading edge and a trailing edge, the guide surface extending a distance into the opening whereby the trailing edge is disposed within the interior space of the housing.
13. The device of claim 12, wherein the housing is a retractor cover.
14. The device of claim 12, wherein the housing is a barrier housing.
15. The device of claim 12, wherein the trailing edge of the guide surface is disposed in close proximity to the retractor spool.
16. The device of claim 12, wherein the guide surface has at least one slope between the leading edge and the trailing edge, wherein the at least one slope causes the leading edge to diverge from an opposing sidewall.
17. The device of claim 16, wherein the at least one slope comprises at least a first slope near the leading edge and at least a second slope near the trailing edge, wherein the guide surface is aligned approximately perpendicular to an axis of the opening near the leading edge and is aligned approximately parallel to the axis of the opening near the trailing edge.
18. The device of claim 12, wherein the guide surface is curvilinear and includes a variable slope between the leading and trailing edges.
19. The device of claim 12, wherein the opening includes a plurality of contoured guide surfaces, at least one of which is adapted to guide the movement of the lateral edges of the strap.
20. The device of claim 12, wherein the guide surface for the opening is formed on a member which is attachable to the housing.
21. The device of claim 20, wherein the member includes at least one locking groove whereby the member can be engaged with the opening by snapping into place.
22. The device of claim 12, wherein the opening is generally quadrangular and includes four walls, onto at least one of which the guide surface is formed.
23. A device for reducing the chances that a twisted portion of a restraint strap will interfere with the operation of a retractor comprising: a housing, a retractor spool, and a restraint strap, the restraint strap being wound on the retractor spool and having a thickness; the housing defining an interior space in which a retractor spool is disposed and having an opening which is adapted for passing the strap therethrough; the opening having an effective height which is between approximately two and eight times the thickness of the restraint strap to allow a double stitched portion of the restraint strap to pass therethrough; the opening having at least one sidewall, with at least a portion of the sidewall having a guide surface, the guide surface being configured to guide the movement of the strap and thereby resist the passing of a twist in the strap through the opening and into the housing; and, the guide surface having a leading edge and a trailing edge, the guide surface extending a distance into the opening whereby the trailing edge is disposed within the interior space of the housing.
24. The device of claim 23, wherein the effective height is between approximately two and six times the thickness of the restraint strap.
25. The device of claim 23, wherein the housing is a retractor cover.
26. The device of claim 23, wherein the housing is a barrier housing.
27. The device of claim 23, wherein the trailing edge of the guide surface is disposed in close proximity to the retractor spool.
28. The device of claim 23, wherein the guide surface has at least one slope between a leading edge and a trailing edge, wherein the at least one slope causes the leading edge to diverge from an opposing sidewall.
29. The device of claim 28, wherein the at least one slope comprises at least a first slope near the leading edge and at least a second slope near the trailing edge, wherein the guide surface is aligned approximately perpendicular to an axis of the opening near the leading edge and is aligned approximately parallel to the axis of the opening near the trailing edge.
30. The device of claim 29, wherein the guide surface is curvilinear and includes a variable slope between the leading and trailing edges.
31. The device of claim 30, wherein the opening includes a plurality of contoured guide surfaces, at least one of which is adapted to guide the movement of the lateral edges of the strap.
32. The device of claim 30, wherein a guide surface for the opening is formed on a member which is attachable to the housing, the guide surface constricting a size of the opening to provide the opening with the effective height.
33. The device of claim 32, wherein the member includes at least one locking groove whereby the member can be engaged with the opening by snapping into place.