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.
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.qstarint.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 Ser. No. 11/776,223, which is 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 Ser. No. 11/847,435, 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 J-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 fully 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 securing 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.
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. In this manner, 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 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 retractor 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 outwardly diverging. In another embodiment, the housing for the retractor 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.
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.
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:
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.
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
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
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 wall 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
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
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 W1×H1 and minor (or effective) dimensions of W2×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 H1:H2, 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
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
Referring again to the embodiment shown in
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
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, 189 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 and/or the inner lips 159, 179, 189 could be continuous.
As best shown by
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
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.