Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2000-11-10
2003-04-01
Bidwell, James R. (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C193S0350SS, C193S037000, C474S191000
Reexamination Certificate
active
06540068
ABSTRACT:
TECHNICAL FIELD
This invention relates to a roller assembly which passes through predetermined points in its travel for use in the field of cargo mover systems, such as in elevators, escalators, and moving walkway systems. More particularly, this invention relates to a rim assembly for the roller assembly of such a system. This invention was developed for lightweight roller assemblies used with elevator doors as the doors are moved between the open and closed positions and has application to other roller assemblies following a defined path used for cargo mover systems.
BACKGROUND OF THE INVENTION
Roller assemblies used in escalator systems and elevator systems typically pass through predetermined points that form a defined path. These systems are of the type that are typically self-propelled or driven externally. The systems that are driven externally may be driven by a cable, belt or chain of both the open or endless type, or by a mechanical mechanism utilizing screw drives or lever arm actuation. In these systems, the roller assembly and the rail on which the roller assembly moves are a defined portion of the system. For example, the shape and the surface characteristics of the rail surface are defined. Since the rail surface is well-defined, expectations for life, low noise and other characteristics are greater than expectations for roller assemblies used on undefined surfaces, such as might be experienced by bicycles, automobiles and moving carts.
Roller assemblies used in escalators and elevators typically have a rim assembly which includes a rim and a ring in solid form that is positioned from the rim. The ring in solid form has requirements for operative characteristics that are very different from the operative requirements for a ring which is in part supported by gas under pressure, such as automobile tires and the like. In particular, roller assemblies used for elevator doors especially have significant requirements for operative characteristics that can be in conflict. Such roller assemblies may be driven or nondriven.
In contrast, roller assemblies used for guiding elevators or used for escalator systems do not have as many demanding operative characteristics even though the roller assembly follows a defined path. Escalator systems typically use nondriven roller assemblies. For example, the nondriven roller assembly may be attached to an operating element for guiding the element, such as a step chain in the escalator system. One example is shown in U.S. Pat. No. 5,137,135 entitled “Escalator Step-Chain Roller” issued to Pietsch et alia. The roller assembly includes a rim assembly having a rim. The rim has a groove bounded by a surface which faces outwardly. A flexible outer ring in solid form is disposed in the groove and is spaced axially from the sides of the groove. The ring has a rolling surface for rolling contact with a second element. In Pietsch, the cooperating second element is an escalator track.
Elevator systems employ both nondriven roller assemblies and driven roller assemblies that have a ring in solid form. Nondriven roller assemblies may be used for guiding movement of an elevator car as the car moves vertically between predetermined locations. These guide roller assemblies are similar to the roller assembly shown in Pietsch and have somewhat similar operating requirements. The guide roller assemblies are distinguished by the need for the roller assembly to rotate at relatively high speeds in comparison to the escalator roller assembly to accommodate the speed of the elevator car.
As discussed earlier, elevator systems also employ door roller assemblies for guiding elevator doors on the car as the doors are opened and closed. The roller assemblies rotate at a lower rotational speed than do guide rollers for guiding the elevator car. The door roller assemblies are lightweight and may be non-driven, rolling as the door is moved; or may be driven, rotating to drive the door.
A nondriven roller assembly may be attached to the door and may roll on a track as the door is moved by another device between the open and dosed positions. A driven roller assembly engages the track and might be attached to the door. These driven roller assemblies, or traction roller assemblies, are driven about an axis of rotation to move the door between the open and closed positions. An example of such a motorized roller assembly is shown in U.S. Pat. No. 5,852,897 entitled “Door Drive” issued to Sukale.
FIG. 1
is a simplified side elevation view of a roller assembly, such as a lightweight roller assembly
10
for elevator doors, and of a rail
12
on which the roller assembly moves. The rail has a plurality of predetermined location points P which form a defined path
13
for the roller assembly
The roller assembly has an axis of rotation A.
FIG. 2
is a cross-sectional view taken through the simplified roller assembly and the rail along the lines
2
—
2
of FIG.
1
. The cross-sectioning plane contains the axis A and passes through the circumferential location L. The circumferential location L is the location at which the maximum force is transmitted from the rail to the roller assembly as the rail reacts to the load imposed by the roller assembly on the rail.
As shown in FIG.
1
and in
FIG. 2
, the roller assembly
10
has a rim assembly
14
. The rim assembly is usable with both a driven and a nondriven roller assembly. The rim assembly has a freestanding rim
16
and a groove
18
bounded by a radially outwardly facing surface
20
. A flexible ring
22
in solid form is disposed in the groove. The ring extends circumferentially and axially about the rim.
The ring
22
has an outwardly facing surface
24
. The outwardly facing surface includes the rolling first surface
26
which adapts the roller assembly to engage the rail. The rolling first surface has an axial width Rs. The rolling first surface under a particular operative condition of the roller assembly is limited to that portion of the outwardly facing surface, which contacts the rail.
A first element, as represented for example by a shaft
28
, is attached to one of the doors. The shaft is disposed about an axis of rotation A. In alternate embodiments the shaft might be part of the roller assembly and attached to another portion of the first element. The rail
12
is a second element and is engaged by the roller assembly
10
. The roller assembly includes a bearing, as represented for example by a sleeve bearing
32
or a roller bearing as shown in Pietsch. The bearing is disposed between the shaft and the rim assembly to enable movement of the rolling first surface
26
of the ring on the rail.
The rim
16
positions and supports the rolling surface of the flexible ring
22
under operative conditions through a support region R against loads acting on the rolling surface. The ring
22
forms the support region R for the rolling surface in the operative condition. The support region extends radially from the rolling surface to the rim and across the width Rs of the rolling surface. In the embodiment shown, the lightweight roller assembly is not absolutely constrained against movement except for the engagement between the ring and the rail. In one sense, it is a self-guiding roller assembly.
The above art notwithstanding, scientists and engineers are working under the direction of applicants assignee to develop new materials or to develop alternative designs and methods for forming a rim assembly having a flexible ring in solid form which would enhance one or more operative characteristics of the rim assembly under different operative conditions.
SUMMARY OF INVENTION
This invention is in part predicated on the realization that cargo mover systems use different kinds of roller assemblies for following a defined path with a flexible ring in solid form. The roller assemblies have operative characteristics which may markedly differ depending on the application chosen for the roller assembly or, in a particular application, may change as operative conditions of the cargo mover system change.
A flexible ring is consi
Croteau Renee H.
Wesson John P.
Bidwell James R.
Fleischhauer Gene D.
Otis Elevator Company
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