Patent Description:
Various slide mechanisms having stability rolling elements are known for repositioning a vehicle seat along a long rail in a vehicle. One known seat sliding device is disclosed in W. Publication <CIT>wherein a vehicle seat is coupled to a rail drive assembly that is slidable within a fixed long rail. The rail drive assembly includes wheels configured to travel along an interior track of the fixed long rail. In addition, stability rolling elements are mounted at an angle to side walls of the rail drive assembly. Front and rear stability rolling elements on each side of the rail drive assembly are operationally coupled by a torsion spring extending in a longitudinal direction.

However, this known seat sliding device lacks spring-loaded stability rollers that are spring-loaded in both lateral and vertical directions to absorb channel variations. In addition, the stability rolling elements of this known seat sliding device includes a plurality of components which can be difficult to assemble. Finally, this exemplary known seat sliding device lacks spring-loaded stability rolling elements that act as a compression spring to resist lateral load applied to the vehicle seat.

<CIT> discloses a long rail assembly for use in a vehicle includes a lower channel, an inverted U-shaped upper channel, a gearbox, a rack, a pinion, a drive shaft, and a motor. The lower channel is adapted to extend longitudinally along a floor of the vehicle. The upper channel is slidably coupled to the lower channel. The gearbox is fixedly secured to and housed within the upper channel. The rack is fixedly coupled to the lower channel and includes gear teeth extending along the rack in a longitudinal direction. The pinion is meshingly engaged with the gear teeth. The drive shaft operatively couples the gearbox to the pinion. The motor is operatively coupled to the gearbox to power drive the upper channel along the lower channel.

It is desirable, therefore, for a rail drive assembly to have a stability roller assembly that is easy to assemble. Further, it is desirable to reduce the number of components in the stability roller assembly. In addition, it is desirable for the stability roller assembly to resist fore-aft load applied to the vehicle seat. It is also desirable that the stability roller assembly can act like a compression spring to resist lateral load applied to the vehicle seat. Finally, it is desirable for the rail drive assembly to have a stability roller assembly that absorbs both vertical and lateral channel and positional variation.

The present invention is a rail drive assembly comprising the technical features as defined in claim <NUM>.

<FIG> illustrate a long rail assembly <NUM> having a rail drive assembly <NUM> configured to transpose the rail drive assembly <NUM> along a fixed long rail <NUM> for vehicle seat adjustment according to embodiments described herein. Directional references employed or shown in the description, figures or claims, such as top, bottom, upper, lower, upward, downward, lengthwise, widthwise, left, right, and the like, are relative terms employed for ease of description and are not intended to limit the scope of the invention in any respect. Referring to the Figures, like numerals indicate like or corresponding parts throughout the several views.

<FIG> illustrates a long rail assembly <NUM> having a rail drive assembly <NUM> for adjusting a position of a vehicle seat <NUM> along a fixed long rail <NUM> according to one embodiment of the present invention. <FIG> shows a vehicle interior <NUM> having a plurality of vehicle seats <NUM> connected to rail drive assemblies <NUM> attached to a vehicle floor <NUM>. A cross-sectional view of the long rail assembly <NUM> of <FIG> taken along section line A-A is shown in <FIG>.

Referring to <FIG>, each vehicle seat <NUM> is supported by at least one leg <NUM> on opposing sides 18A, 18B of the vehicle seat <NUM>, and optionally front and rear legs <NUM>, <NUM> on the opposing sides 18A, 18B of the vehicle seat <NUM>. Each rail drive assembly <NUM> travels along one of the fixed long rails <NUM> attached to the vehicle floor <NUM>. Each vehicle seat <NUM> travels along a pair of fixed long rails <NUM>, <NUM>' when the vehicle seat <NUM> is repositioned between a first seat location <NUM> and a second seat location <NUM>, shown as vehicle seat <NUM>' attached to rail drive assembly <NUM>'. The fixed long rails <NUM> can extend for any length suitable for an intended application. Likewise, any suitable number of fixed long rails <NUM> can be positioned on the vehicle floor <NUM> as desired for an intended application. Thus, the long rail assembly <NUM> allows for improved vehicle seat <NUM> position adjustment since the vehicle seat <NUM> coupled to at least one rail drive assembly <NUM> is repositionable to any seat position <NUM>, <NUM> along the at least one fixed long rail <NUM>. In certain embodiments, the rail drive assembly <NUM> is a manual rail drive assembly that is manually repositioned along the fixed long rail <NUM>. In other embodiments, the rail drive assembly <NUM> is a power rail drive assembly configured to be automatically repositioned along the fixed long rail <NUM>.

Returning to <FIG> and <FIG>, the fixed long rail <NUM> has a generally U-shaped cross-section <NUM> in profile extending in a longitudinal direction, a bottom wall <NUM>, opposing first and second side walls <NUM>, <NUM>, an interior cavity <NUM>, and a top wall <NUM> having an elongated opening <NUM> extending in a longitudinal direction. Extending between each one of the first and second side walls <NUM>, <NUM> and terminating at the adjacent top wall <NUM> is an upper side wall <NUM>, <NUM>. The first and second upper side walls <NUM>, <NUM> extend at an angle from the adjacent side wall <NUM>, <NUM>. The fixed long rail <NUM> is a stamped, formed, molded, and/or rolled section of metal, plastic, or combinations of metal and plastic materials and has a length selected based on a specific application. It should be appreciated that the size and shape of the fixed long rail <NUM> may vary without altering the scope of the invention. The dimensions of the fixed long rail <NUM>, including the cross-sectional profile <NUM>, are selected, in part, based on generally known engineering calculations, finite element analysis (FEA), and physical testing.

Also shown in <FIG> and <FIG>, the rail drive assembly <NUM> includes an elongated upper channel <NUM> having a generally W-shape cross-section <NUM> in profile, opposing first and second side walls <NUM>, <NUM> and a top wall <NUM> extending between the opposing first and second side walls <NUM>, <NUM>. An axle <NUM> extends laterally through a hollow tube <NUM> extending between the opposing side walls <NUM>, <NUM>. A wheel <NUM> is fixedly coupled to each end 106A of the axle <NUM>. The rail drive assembly <NUM> shown in the embodiment of <FIG> includes a pair of wheels <NUM> positioned adjacent to opposing ends 94A, 94B of the upper channel <NUM>. While not shown, the wheels <NUM> can be replaced by rollers and/or glides. Any number and/or combination of wheels <NUM>, rollers, and/or glides may be used as suitable for an intended application. Further, each wheel <NUM> or roller can be rotationally attached to the upper channel <NUM> using a shaft (not shown) fixedly coupled to one of the side walls <NUM>, <NUM> of the upper channel <NUM>.

In the embodiment shown in <FIG>, each pair of wheels <NUM> is attached to carrier <NUM> having a generally inverted U-shape cross-section in profile. The carrier <NUM> includes an upper wall 112A extending between opposing first and second side walls 112B, 112C. The axle <NUM> passes through a hole 112D in each of the opposing first and second side walls 112B, 112C. The carrier <NUM> is fixedly coupled to the upper channel <NUM>.

As shown in <FIG>, the rail drive assembly <NUM> includes spaced apart first and second flexible stability roller assemblies <NUM>, <NUM>'. Each of the first and second flexible stability roller assemblies <NUM>, <NUM>' is positioned near a respective end 94A, 94B of the upper channel <NUM>.

Referring to <FIG>, the flexible stability roller assemblies <NUM>, <NUM>' are fixedly coupled to a lower side 102A of the top wall <NUM> of the upper channel <NUM>. Each flexible stability roller assembly <NUM>, <NUM>' includes first and second stability rollers 118A, 118B rotationally coupled to a flexible wing bracket <NUM>. In the embodiment shown in <FIG>, a center portion 120A of the flexible wing bracket <NUM> is welded to the upper channel <NUM> in two spaced apart locations 124A, 124B. In certain embodiments, the flexible wing bracket <NUM> is welded to the upper channel <NUM> in one location 124A, 124B. It will be understood that the flexible wing bracket <NUM> can be fixedly coupled to the upper channel <NUM> through other known methods including but not limited to a mechanical fastener, crimping, welding, and press fit.

The flexible wing bracket <NUM> is shown removed from the rail drive assembly <NUM> in <FIG>. The flexible wing bracket <NUM> is a flexible bracket formed out of a metal material such as high strength low alloy (HSLA) steel. One exemplary suitable HSLA steel is Society of Automotive Engineers (SAE) grade <NUM>. It will be understood that other grades and types of steel can be used in alternate embodiments without altering the scope of the invention. Referring to <FIG>, the flexible wing bracket <NUM> has a general W-shape with opposing first and second side portions 120B, 120C extending from the center portion120A. Each of opposing first and second wing portions 120D, 120E extend from the adjacent first and second side portions 120B, 120C. In the embodiment shown in <FIG>, each of the first and second side portions 120B, 120C are connected to the center portion 120A by a first curved portion 120F. The first and second wing portions 120D, 120C are connected to the adjacent side portions 120B, 120C by a second curved portion <NUM>. The flexible wing bracket <NUM> has an unconstrained profile <NUM> (i.e., a "free" profile) in <FIG>. The first and second side portions 120B, 120C project from the center portion 120A an angle <NUM> of about ninety degrees. However, the specific size, shape, and orientation of the center portion 120A and the first and second side portions 120B, 120C are selected to fit within the upper channel <NUM>. As such, the size, shape, and orientation of the center portion 120A and the first and second side portions 120B, 120C will vary to fit alternate embodiments of the upper channel <NUM>.

Also shown in <FIG>, the first and second wing portions 120D, 120E project away from the adjacent first and second side portions 120B, 120C at an angle <NUM> of about forty degrees. It will be understood that the angle <NUM> between the first and second wing portions 120D, 120E and the adjacent first and second side portions 120B, 120C can vary in alternate embodiments. For example, in certain embodiments the unconstrained angle <NUM> between the first and second wing portions 120D, 120E and the adjacent first and second side portions 120B, 120C, is selected to be between thirty degrees and fifty degrees, as a non-limiting example. It will be understood that the unconstrained angle <NUM> is selected based in part on the specific profile and dimensions of the fixed long rail <NUM>. In the embodiment shown in <FIG>, the flexible wing bracket <NUM> has a longitudinal length between opposing first and second end surfaces 140A, 140B of about <NUM>. In addition, the exemplary flexible wing bracket <NUM> has a thickness of about <NUM> as measured between opposing first and second surfaces 142A, 142B of the center portion 120A. It will be understood that the longitudinal length of the flexible wing bracket <NUM> between the first and second end surfaces 140A, 140B can vary without altering the scope of the invention. Likewise, the thickness of the flexible wing bracket <NUM> between opposing first and second surfaces 142A, 142B can vary without altering the scope of the invention. The flexible wing bracket <NUM> is alternatively formed out of sheet stock that has been stamped, molded, formed, and/or bent, as non-limiting examples, into the desired shape.

Each of the first and second wing portions 120D, 120E includes an aperture <NUM> positioned near a distal end <NUM> of the first and second wing portions 120D, 120E and extending between the opposing first and second surfaces 142A, 142B, as shown in <FIG>. The aperture <NUM> is sized and shaped to matingly engage with a shaft <NUM> extending from the stability roller 118A, 118B. The stability rollers 118A, 118B are optionally rotationally coupled to the associated shaft <NUM> with the associated shaft <NUM> being fixedly coupled to the flexible wing bracket <NUM>. Alternatively, the shaft <NUM> is rotationally coupled to the flexible wing bracket <NUM> with the stability roller 118A, 118B being fixedly coupled to the shaft <NUM>. In addition, a washer <NUM> is assembled between the flexible wing bracket <NUM> and the stability roller 118A, 118B. In certain embodiments, the washer <NUM> is fixedly coupled to the shaft <NUM>, fixedly coupled to the stability roller 118A, 118B, or is a separate component assembled onto the shaft <NUM>.

The flexible stability roller assembly <NUM>, <NUM>' is shown assembled with the upper channel <NUM> in <FIG>. The stability rollers 118A, 118B are shown assembled with the flexible wing bracket <NUM>. The flexible wing bracket <NUM> is sized and shaped such that distal ends <NUM> of the stability rollers 118A, 118B have a designed interference with the fixed long rail <NUM>. More specifically, the distal ends <NUM> of the stability rollers 118A, 118B extend beyond at least the inner surface 74A, 78A of the upper side walls <NUM>, <NUM> when the flexible wing bracket <NUM> is unconstrained.

<FIG> shows the flexible stability roller assembly <NUM>, <NUM>' assembled with the fixed long rail <NUM>. A comparison of the unconstrained profile <NUM> and the constrained profile <NUM>' of the flexible wing bracket <NUM> is shown in <FIG>. Since the unconstrained profile <NUM> of the flexible wing bracket <NUM> has a designed interference with the fixed long rail <NUM>, each of the distal ends <NUM> of the stability rollers 118A, 118B are pressed inward and downward, as represented by arrow <NUM>, during assembly with the fixed long rail <NUM>. In addition, each of the first and second side portions 120B, 120C of the flexible wing bracket <NUM> are deflected inward, as illustrated by arrow <NUM>. The flexing of the flexible wing bracket <NUM> moves the distal end <NUM> of the unconstrained profile <NUM> to abut the inner surface 74A, 78A of the upper side walls <NUM>, <NUM>, as illustrated by distal end <NUM>' of the constrained profile <NUM>'. Since the flexible wing bracket <NUM> is flexible and essentially acts as a spring, the flexible wing bracket <NUM> can accommodate for variation in the dimensions of the fixed long rail <NUM> as well as accommodating for variation within the rail drive assembly <NUM>. The elastic deformation of the flexible wing bracket <NUM> absorbs channel variation in both up-down and cross-car directions. The elastic deformation during assembly can provide reaction force to the stability rollers 118A, 118B. Since the stability rollers 118A, 118B contact the fixed long rail <NUM> at an angle, the reaction force from the flexible wing bracket <NUM> can provide resistance to both up-down and cross-car variation from the rail drive assembly <NUM>. In addition, the elastic deformation of the flexible wing bracket <NUM> during assembly with the fixed long rail <NUM> acts as a compression spring to resist lateral load applied to the vehicle seat <NUM>. Further, the flexible wing bracket <NUM> assists with centering the rail drive assembly <NUM> within the fixed long rail <NUM> since the flexible wing bracket <NUM> maintains a spring bias holding the stability rollers 118A, 118B against the upper side walls <NUM>, <NUM> of the fixed long rail <NUM>.

In contrast, an exemplary known long rail assembly 10P having spring-loaded stability roller elements <NUM>, <NUM> is shown in <FIG> and <FIG>. Elements that are the same or similar to those used above in the embodiment shown in <FIG> have the same reference numbers for simplicity. Referring to <FIG>, the known long rail assembly 10P includes a known rail drive assembly 12P configured to travel along a fixed long rail 14P. The known rail drive assembly 12P includes an upper channel <NUM> having opposing side walls <NUM>, <NUM> extending from a top wall <NUM> forming an inverted U-shape and extending between opposing ends 94A, 94B of the upper channel <NUM>. Wheels <NUM> are rotationally coupled to the upper channel <NUM> near each end 94A, 94B of the upper channel <NUM>. As shown in <FIG>, the fixed long rail 14P is generally U-shaped with opposing side walls <NUM>, <NUM> extending between a bottom wall <NUM> and a top wall <NUM> of the fixed long rail 14P. Extending between each side wall <NUM>, <NUM> and the adjacent top wall <NUM> is a curved portion <NUM> having a large corner radius <NUM>.

Referring to <FIG>, the known stability rolling elements <NUM>, <NUM> are rotationally coupled to each side wall <NUM>, <NUM> of the upper channel 94P. <FIG> is a cross-sectional end view taken along section B-B of <FIG> showing the stability rolling elements <NUM>, <NUM> being mounted at an angle <NUM> of about thirty degrees to the side walls <NUM>, <NUM> of the upper channel 94P. Each stability rolling element <NUM>, <NUM> includes a roller <NUM>, an upper arm <NUM>, <NUM>, a lower arm <NUM>, <NUM>, and a support stud <NUM>. Each roller <NUM> is rotationally coupled to the associated upper arm <NUM>, <NUM>. Each upper arm <NUM>, <NUM> is rotationally coupled to the associated support stud <NUM>. Each support stud <NUM> is fixedly coupled to the adjacent side wall <NUM>, <NUM> at a mounting angle <NUM>, such as about <NUM> degrees as shown in <FIG>. In addition, the upper arm <NUM> is fixedly coupled to the lower arm <NUM> so they are linked together to move as one arm.

Referring to <FIG>, a first end 208A of a torsion spring <NUM> is connected to the lower arm <NUM> of the known first stability rolling element <NUM>. A second end 208B of the torsion spring <NUM> is connected to the lower arm <NUM> of the known second stability rolling element <NUM>. The torsion spring <NUM> biases the rollers <NUM> of the stability rolling elements <NUM>, <NUM> towards the adjacent fixed long rail 14P curved portions <NUM>. In addition, the torsion spring <NUM> induces a longitudinal spring bias into the stability rolling elements <NUM>, <NUM>, as illustrated by arrow <NUM> shown in <FIG>. Further, the known stability rolling elements <NUM>, <NUM> can rotate with respect to the associated pivot shaft <NUM>, as illustrated by arrows <NUM>. The roller <NUM> absorbs variations in both a lateral and a vertical directions of the fixed long rail <NUM> since the roller <NUM> is angled at about <NUM> degrees from the side walls <NUM>, <NUM> of the upper channel <NUM>.

However, the stability rolling elements <NUM>, <NUM> of the known long rail assembly 12P shown in <FIG> and <FIG> require a plurality of parts, including the upper arm <NUM>, <NUM>, the lower arm <NUM>, <NUM>, the support stud <NUM>, and the torsion spring <NUM>. In the embodiment shown in <FIG>, these components have been replaced by a single flexible wing bracket <NUM>. The reduction in the number of components directly reduces the cost and complexity of the long rail assembly <NUM> in comparison to the known long rail assembly 12P.

In addition, assembly of the flexible wing bracket <NUM> with the fixed long rail <NUM> induces a lateral spring bias load into the flexible wing bracket <NUM>, as illustrated by arrow <NUM> shown in <FIG>. The torsion spring <NUM> of the known long rail assembly 12P induces a longitudinal spring bias <NUM> into the stability rolling elements <NUM>, <NUM>. The known long rail assembly 12P relies on the upper arms <NUM>, <NUM> being oriented at about a thirty degree angle with respect to the adjacent side wall <NUM>, <NUM> of the upper channel <NUM> in combination with the curved portion <NUM> of the side walls <NUM>, <NUM> of the fixed long rail 14P to laterally bias the stability rolling elements <NUM>, <NUM> towards the side walls <NUM>, <NUM> of the fixed long rail 14P. The flexible wing bracket <NUM> of the embodiment shown in <FIG> actively spring biases the stability rollers 118A, 118B towards the adjacent upper side wall <NUM>, <NUM> of the fixed long rail <NUM>. As such, the flexible wing bracket <NUM> actively laterally stabilizes the upper channel <NUM> within the fixed long rail <NUM>.

Claim 1:
A rail drive assembly (<NUM>) for transposing a vehicle seat (<NUM>) along a fixed long rail (<NUM>), the rail drive assembly (<NUM>) comprising:
an elongated upper channel (<NUM>) having a generally inverted U-shaped cross-section (<NUM>) in profile, the upper channel (<NUM>) having opposing first and second side walls (<NUM>, <NUM>) and a third wall (<NUM>) extending between the first and second side walls (<NUM>, <NUM>); and
a flexible stability roller assembly (<NUM>, <NUM>'),
characterised in that the flexible stability roller assembly (<NUM>, <NUM>') comprises a flexible wing bracket (<NUM>) and first and second stability rollers (118A, 118B) rotationally coupled to respective first and second wing portions (120D, 120E) of the flexible wing bracket (<NUM>), the flexible wing bracket (<NUM>) having a generally W-shaped cross-section in profile with the opposing first and second wing portions (120D, 120E) extending at a first angle from adjacent first and second side portions (120B, 120C), respectively, and the first and second side portions (120B, 120C) extending at a second angle different from the first angle from a center portion (120A), and wherein the center portion (120A) of the flexible wing bracket (<NUM>) is fixedly coupled to the third wall (<NUM>) of the upper channel (<NUM>).