Electricity: conductors and insulators – Covers or face plates
Reexamination Certificate
2000-05-20
2001-10-02
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Covers or face plates
C174S067000
Reexamination Certificate
active
06297451
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
BACKGROUND OF THE INVENTION
This invention is directed to a control system for detecting the presence of packages that may accumulate on a rollerless conveyor that provides long accumulation zones in the conveyor without sacrificing accumulation density so as to simplify accumulation control zones for sensing packages that may be moved along the conveyor.
The prior art of accumulating packages on a conveyor wherein the package is moved along a plurality of rollers by a chain that is elevated to support the package for movement relative to frame members has means to support the package in a stationary position when not lifted by the chain for transportation to an outlet. Such a conveyor is disclosed in Wyman U.S. Pat. No. 3,930,573 of Jan. 6, 1976.
A variation in the prior art is disclosed in Bowman U.S. Pat. No. 3,934,707 of Jan. 27, 1976 which employs a continuously drawn belt with ways alongside the belt which are movable vertically to vary the relative vertical position between an accumulation position wherein the support surface of the ways is above the conveyor belt causing package accumulation and a package drive position wherein the support surface of the way is below the conveyor belt causing package movement.
The prior art includes a conveyor system of the character in Holt U.S. Pat. No. 4,149,626 of Apr. 17, 1979 in which spaced conveyor surfaces of multiple rollers are occupied by a flat link chain which is vertically movable relative to the spaced roller surfaces at selective portions to move packages.
Furthermore, the prior art Garro U.S. Pat. No. 5,085,311 of Feb. 4, 1992 has disclosed a belt or chain with wear surfaces along both sides of the belt or chain for conveying packages, and apparatus for displacing the belt or chain or the wear surface relative to each other to provide an in-line accumulator having a zero backline pressure.
BRIEF SUMMARY OF THE INVENTION
To overcome the prior art deficiencies it is an important object of this invention in rollerless accumulation conveyors to have a control scheme that enables the use of long accumulation zones without sacrificing accumulation density to reduce the quantity or number of zones required, thereby resulting in fewer elements in a control system.
Another object is to employ a control system that responds to the accumulation of packages at a discharge zone to supervise the performance of the system by delaying removal of conveyor drive contact to obtain a high package density in such zone, and also initiate final conveyor drive removal to prevent package damage once maximum density is obtained.
A further object of the invention is to provide photocell means to exhaust the pressure medium in a control system so as to maximize package accumulation density when the package charge rate is low, and avoiding excessive package line pressure when the charge rate is high.
Another object of the invention is to provide the accumulation conveyor with a control system having a location in a frame to provide a convenient working surface to perform adjustments when the protective cover for the control system is manually opened to allow for service access.
REFERENCES:
patent: 2526606 (1950-10-01), Gregg
patent: 3676974 (1972-07-01), Daly
patent: 4851612 (1989-07-01), Peckham
patent: 5045640 (1991-09-01), Riceman
patent: 5389740 (1995-02-01), Austin
patent: 5829554 (1998-11-01), Benson et al.
Alvey Systems, Inc.
Estrada Angel R.
Polster Lieder Woodruff & Lucchesi L.C.
Reichard Dean A.
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