FIELD OF THE INVENTION

The present invention relates to automotive window regulators. More specifically, the present invention relates to a lift plate for a window regulator that resists backdrive forces.

BACKGROUND OF THE INVENTION

Automotive window regulators are required to resist backdrive in order to prevent a partially opened window from being forced down from the outside of the vehicle, such as in a break-in attempt. Current industry practice is to resist backdrive by using a torsion spring clutch in a manual window regulator, and by the electric motor gear ratio in a power window regulator. The disadvantages of both these systems is that the complete window regulator must be robust enough to withstand the backdrive force since the transmitted load path extends all the way from the window glass to the lift plate to the drive assembly (either a manual crank assembly or a power motor). In addition, the traditional methods of resisting backdrive create inefficiencies when the window regulator is operated normally. In a manual system the clutch torque, which could be as high as 20% of the total operating torque, must be overcome before motion is transmitted to the lift plate. In a power system, single-start worms are required in the motor gearset to ensure suitable backdrive gear efficiency, but single-start worms also create a very low driving efficiency for normal operation of the window regulator.

It is therefore desired to provide a window regulator that resists backdrive in a manner that mitigates or obviates at least one of the above-described disadvantages.

SUMMARY OF THE INVENTION

The present invention provides a window regulator that resists backdrive forces directly at the lift plate and rail, rather than by the drive assembly. A locking shoe is mounted within the lift plate and selectively frictionally engages the rail while the drive assembly is at rest. Thus, any backdrive forces are transmitted from the

window glass to the lift plate, and then directly to the rail, avoiding the drive assembly. A release fork that is coupled to the drive cable automatically disengages the locking shoe when the drive assembly is activated, and engages the locking shoe when the drive assembly disengages.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein:

Figure 1 shows a perspective view of a portion of a window regulator in accordance with an aspect of the invention;

Figure 2 shows a perspective view of a lift plate located on the window regulator shown in Fig. 1;

Fig 3 shows a perspective view of a locking shoe and a nipple housing located on the window regulator shown in Fig. 1;

Fig 4 shows a perspective view of the nipple housing shown in Fig. 3 with the locking shoe removed;

Fig 5 shows a perspective view of a the locking shoe shown in Fig. 3 from an alternate angle;

Fig 6 shows a perspective view of the nipple housing shown in Fig 4 from an alternate angle; and

Fig 7 shows a perspective view of the nipple housing shown in Fig. 4 and 6 from an alternate angle.

DETAILED DESCRD7TION OF THE INVENTION

Referring now to Fig. 1, a portion of a window regulator 10 is shown. Window regulator 10 includes a rail 12 that slidably mounts a lift plate 14. Lift plate 14 is operable to traverse rail 12 using a drive cable 16 that is wound around a conventional drive and pulley assembly 18 (not shown). A locking shoe 20 is slidably mounted to rail 12 and retained within a cutout on lift plate 14. Additionally, a nipple housing 22 floats within the cutout on lift plate 14.

Rail 12 is preferably formed from a unitary piece of metal or plastic and can be manufactured by conventional molding, stamping or roll forming techniques. Rail 12 is attached to a substructure (not shown) of a vehicle door frame via conventional fasteners. Alternatively, rail 12 can be attached to or otherwise formed as part of the substrate of a door hardware module. Rail 12 provides an opposing first surface 21 and second surface 23 (not shown), and further includes a parallel first edge 24 and a second edge 26 that run longitudinally along rail 12. An arcuate flange 28 is integrally formed from first edge 24 and curves away from first surface 21 of rail 12, providing a mounting surface for lift plate 14 (described in greater detail below). Proximate to the second edge 26 is a semicircular groove channel 30 that runs parallel to second edge 26.

Lift plate 14 is raised or lowed by drive and pulley assembly 18 (not shown). As known to those of skill in the art, drive and pulley assembly 18 typically includes a pulley mounted at each end of rail 12, and a cable drum mounted to window regulator 10 between the two pulleys, but displaced away from rail 12. Other arrangements of pulleys and cable drums will occur to those of skill in the art, and are within the scope of the invention. For example, the pulleys or the cable drum could be mounted directly to a door hardware module, instead of rail 12. Drive cable 16 is threaded around the cable drum and pulleys, and is described in greater detail below, terminates with a nipple 17 at each end inside nipple housing 22 located within lift plate 14. The cable drum is further coupled to a conventional manual crank system or an electric motor to move the lift plate along rail 12.

Referring now to Fig. 2, lift plate 14 is shown in greater detail. Lift plate 14 is preferably formed from a unitary piece of metal or plastic and can be manufactured by conventional casting or molding techniques. Lift plate 14 is adapted to mount a window glass (not shown) on a first surface 29 using conventional fasteners, tabs or the like. As described earlier, lift plate 14 is slidably mounted to rail 12. An arcuate quadrant slot 32 is provided in an opposing second surface 31 of lift plate 14 and is complementarily fitted over arcuate flange 28. This mounting configuration provides a degree of axial freedom of rotation of lift plate 14 around rail 12 without affecting the locking or unlocking action of lift plate 14 (described in greater detail below). Axial freedom of rotation provides for correct glass tracking and alignment of the window glass with the glass run channels in the door frame (not shown). As mentioned earlier, lifting plate 14 further includes a cutout 34 between first surface 29 and second surface 31. In the current embodiment, cutout 34 includes a generally rectangular area 36 in communication with a generally oval area 38. As can be seen in Fig. 1 and is described in greater detail below, locking shoe 20 is retained against the sidewalls of rectangular area 36 and nipple housing 22 floats more loosely within oval area 38. Two cable passages 40 coaxial with rail 12 extend from opposing side walls 33 of lifting plate 14 into oval area 38 and provide means to thread drive cable 16 through to nipple housing 22.

Referring now to Figs. 3 to 5, locking shoe 20 is described in greater detail. Locking shoe 20 is generally 'C shaped ¹ piece of metal or plastic and is fitted over both surfaces of rail 12 at the second edge 26. Locking shoe 20 includes a sidewall 44 that abuts second edge 26 of rail 12, a retaining wall 46 that extends around a portion of first surface 21 that includes groove channel 30, and a retaining wall 48 extending around a portion of second surface 23 that includes the under-surface of groove channel 30. A flange 50 with a central cutout 52 depends from retaining wall 46. Locking shoe 20 is located around the second edge 26 of rail 12 by two resiliant balls 54 (Fig 4) that are retained between groove channel 30 in the rail and two symmetrically oriented grooves 56 formed on the interior surface of retaining wall 46 of locking shoe 20. Preferably, balls 54 are metal bearing. A lip 58 is formed between the edge of grooves 56 and the inner surface of sidewall 44. A fin 60, acting as a

fulcrum is integrally formed on the inner surface of sidewall 44 and retaining wall 46 midway between the two grooves 56. Both flanges 50 and lip 58 slope away from first surface 21 on rail 12 as they extend outwards from a centerline defined by central cutout 52 and fin 60. An opposing pair of ramps 62 are situated on the inner surface of retaining wall 48 and provide a reaction force against the underside of groove channel 30 on second surface 23. On each side of fin 60, ramps 62 are sloped inversely to flange 50 and lip 58.

Referring now to Figs. 4, 6 and 7, nipple housing 22 is described in greater detail. Nipple housing 22 is located in oval area 38 of cutout 34. A chamber 64 provided inside nipple housing 22 is adapted to retain the one or two nipples 17 located at the ends of drive cable 16. A slot 66 is provided in a portion of the sidewalls of nipple housing 22 for drive cable 16 to pass through into chamber 64. Additionally, a gap 68 is provided in the sidewall of nipple housing 22 to fit nipples 17 into chamber 64 through during assembly of window regulator 10.

Floating nipple housing 22 further includes an integrally molded release fork 70. Release fork 70 includes a central finger 72 disposed between two spring fingers 74. The ends of spring fingers 74 are generally parallel to central finger 72.Central finger 72 passes through central cutout 52 into locking shoe 20. A slot 76 on the end of central finger 72 locates nipple housing 22 on fin 60 (Fig. 5) and allows nipple housing 22 to partially pivot there around. The range of pivotal motion of nipple housing 22 is limited by the sidewalls of central cutout 52 in flange 52. Spring fingers 74 abut against lip 58 and urge release fork 70 into a neutral, "locked" position equidistant between the two grooves 56 and perpendicular to the axis of motion in locking shoe 20. Additionally, spring fingers 74 preload spherical balls 54 into full contact with grooves 56 and groove channel 30 when lift plate 14 is stationary, locking lift plate 14. Release fork 70 has two cam faces 78 that are aligned with the longitudinal centerline of groove channel 30 and with the center of balls 54 (Fig. 4). The ratio of the overall length of central finger 72 to the distance from its base against sidewall 46 to the center of cam faces 78 provides a mechanical advantage which reduces the effort required to release spherical balls 54.

The rotation of release fork 70, due to the movement of drive cable 16 locks and unlocks lift plate 14. At rest, lift plate 14 is effectively locked. The relationship between the angle subtended by groove channel 30 on rail 12 and grooves 56 (formed by flange 50 and lip 58) on locking shoe 20, together with the operating coefficient of friction in the locking shoe 20 and rail 12, are such that locking shoe 20 is locked in place to rail 12 by a wedging action by the leading ball 54 generally perpendicular to first surface 21 on rail 12. Backdriving of window regulator 10 is resisted directly at lift plate 14 - force is transmitted from the window glass to the lift plate, and subsequently to locking shoe 20. The backdrive force wedges the leading balls 54 between its groove 56 and groove channel 30. The opposing ramp 48 provides a reaction force against the underside of groove channel 30 on rail 12. Force is then transmitted directly to rail 12, and not down drive cable 16 to the drive assembly. A small clearance is provided between cam faces 78 and balls 54 to ensure release fork 70 does not dislodge the locking ball 54.

Lift plate 14 is effectively unlocked by engaging drive and pulley assembly 18. The initial movement of drive cable 16 causes nipple housing 22 to rotate slightly in lift plate 14 around fin 60, bringing the leading cam face 78 of release fork 70 into contact with the leading ball 54. This contact pushes the leading ball 54 out of secure engagement between groove channel 30 and groove 56. At this point, lift plate 14 is still stationary. Continued movement of drive cable 16 then rotates nipple housing 22 further until the leading sidewall of nipple housing 22 comes into contact with the side face of rectangular area 36 on cutout 34 so that nipple housing 22 reacts against lip plate 14. Then, drive cable 16, locking shoe 20, nipple housing, 22 and lift plate 14 then move together as a single unit. Additionally, as nipple housing 22 is rotated around fin 60, the trailing spring finger 74 is restrained by the slope of lip 58 and flange 50, placing the trailing spring finger 74 under tension. When the movement of drive cable 16 stops, the release of tension forces in drive cable 16 and the trailing spring fingers 74 combine to return nipple housing 22 and balls 54 to a locked position between groove channel 30 and grooves 56, as is described above. Only the

leading ball 54 needs to be released by release fork 70 as the trailing ball 54 has no influence on the motion of lift plate 14.

The above-described embodiments of the invention are intended to be examples of the present invention and alterations and modifications may be effected thereto, by those of skill in the art, without departing from the scope of the invention which is defined solely by the claims appended hereto.