Conveyors: power-driven – Conveyor arrangement for selecting among plural sources or... – By loading or unloading section at selected one of a...
Reexamination Certificate
2001-09-28
2004-11-09
Hess, Douglas (Department: 3653)
Conveyors: power-driven
Conveyor arrangement for selecting among plural sources or...
By loading or unloading section at selected one of a...
C198S370030, C198S890000
Reexamination Certificate
active
06814216
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to conveyor sortation systems and, in particular, to a positive displacement sorter of the pusher shoe and slat configuration.
Positive displacement sortation conveyors are known having a main conveying surface and diverter shoes that are generally used to displace articles laterally on the main conveying surface, such as when the articles are to be diverted upon one or more spur conveyor lines typically placed at an angle to the main conveying surface. Such conveyors may include a pair of endless chains and a plurality of members, such as slats, connected at their opposite ends to the chains in order to provide a moving conveyor surface. Each slat, or every other slat, is fitted with a pusher or diverter shoe mounted in a manner such that the shoe may glide laterally across the slat. Movement of the shoe is guided by a guide track beneath the conveying surface. At the loading end of the sortation system, the shoes have a particular orientation with respect to the conveying surface. When an article is to be diverted to a particular spur line, a diverter assembly is actuated to switch a portion of the shoes adjacent the article onto one or more diagonal tracks causing the effected shoes to glide across the slats to divert the article. Examples of such positive displacement sorters include commonly assigned U.S. Pat. Nos. 4,738,347 and 5,127,510. Other examples include U.S. Pat. Nos. 3,361,247; 5,409,095; and 4,884,677; and European Published Patent Applications EP 0 602 694 B1 and EP 0 444 734 A1.
In many instances, sortation conveyors are driven by rotary motors operatively connected to sprockets which propel the chains. As the application in which the sortation conveyors are used becomes increasing large, the size of the rotary motors must correspondingly increase in order to provide sufficient power to propel the longer conveying surface, as well as achieve the desired throughput. As the size of the motors and sprockets increases in order to meet the additional power requirements, the noise issued from the rotary motor, as well as the sizes of the sprockets and chains, correspondingly increase.
There is a long-felt need to increase the throughput of conveyor systems. Sortation conveyors and their associated induction conveyors are often the most challenging portion of the conveyor system to handle increasing demands for article throughput. Increase in throughput can be achieved by increasing the speed of the conveying surface. However, there are difficulties in continuously increasing the speed of the conveying surface. Another way to increase throughput is to decrease the gap between articles while ensuring sufficient gap to allow the articles to be properly diverted to their destination spur. As gaps get smaller to increase throughput, the necessity to maintain control over the gaps increases. Because gaps are established by placement of articles on the conveying surface of the sorter and the articles are placed on the conveying surface of the sorter from an induct conveyor, the requirement for smaller gaps increases the desirability to place and maintain the articles in proper position on the conveying surface of the sorter.
SUMMARY OF THE INVENTION
The present invention provides a unique positive displacement sorter apparatus and method of controlling same. Aspects of the present invention may be utilized with conventional motors, and a unique linear motor drive system and method of the present invention may be utilized with other positive displacement sorter configurations than those disclosed herein.
A positive displacement sorter apparatus, according to an aspect of the invention, includes means for defining a plurality of slats that are interconnected, thereby defining an endless web. An upper run of the web defines a conveying surface. The apparatus further including means for defining a plurality of pusher shoes gliding along at least some of the slats to laterally displace articles on the conveying surface. The apparatus further includes secondary means for defining a plurality of linear motor secondaries at the slats, primary means for inducing thrust in the secondaries and thereby propelling the web and control means for controlling the primary means.
The apparatus may include a wheel apparatus for supporting the web, the wheel apparatus having wheels at some of the slats rotating about an axis projecting from an interior of the associated slats. Each of the slats may have an upper surface portion that is substantially planar. Each of the slats may have an outer surface that does not extend above the conveying surface for all orientations of the slats. The primary and secondary means may be either a synchronous linear motor system or a non-synchronous linear motor system. The primary means may be between the upper and lower runs of the web. The secondary means may include magnet plates in the interior of the slats. The primary means may be adjacent an upper run of the web for propelling slats in the upper run and be positioned where the pusher shoe diverter assemblies are not positioned. The primary means may be adjacent a lower run of the web for propelling slats in the lower run from above and produce sufficient thrust to propel the web without elevating the slats in the lower run.
A positive displacement sorter apparatus, according to an aspect of the invention, includes a plurality of interconnected slats defining an endless web, the upper portion of the web defining a conveying surface and pusher shoes gliding along at least some of the plurality of slats to laterally displace articles on the conveying surface. Each of the slats has an outer surface including upper, lower and side surface portions. Either the front or rear surface portion is generally concave. The other of the front or rear surface portions is generally convex. In this manner, adjacent slats have cooperatively faced portions. Among the many advantages that may be achieved, this aspect of the invention provides for generally uniform gaps between the slats irrespective of orientation of the slats, such as when the slats are traveling between upper and lower web portions and the transition portions between the upper and lower web portions.
One of the generally concave and generally convex surface portions may have a first enclosing radius of curvature and the other of the generally concave and generally convex surface portions may have a second enclosing radius of curvature with the first and second enclosing radii having a common locus. At least one of the generally concave and generally convex surface portions may have a planar segment or may have an arcuate segment. The sorter apparatus may include a wheel apparatus for supporting the slats. The wheel apparatus may have a slat-support wheel at a locus of the radius of one of the arcuate portions. The upper surface portion of the slats may be substantially planar. The outer surface of the slats may be at or below the conveying surface for all orientations of the slats.
A positive displacement sorter apparatus, according to another aspect of the invention, includes a plurality of interconnected slats defining an endless web having upper and lower runs and transition portions between the upper and lower runs. The upper run of the web defines a conveying surface. Pusher shoes glide along at least some of the plurality of slats to laterally displace articles on the conveying surface. A linear motor propulsion system is provided for propelling the web. The linear motor propulsion system includes at least one motor primary and a plurality of motor secondaries at the slats. The at least one motor primary is between the upper and lower runs. Among the many advantages that may be achieved, the positioning of the at least one motor primary between the upper and lower runs reduces the vertical height of the sorter apparatus. This allows the sorter apparatus to be adapted to an increased number of applications without taking special precautions to accommodate a higher sorter apparatus.
A posi
Black Andrew R.
Bozarth Charles W.
Ko Clyde Miin-Arng
Veit Frank W.
Verploegen Rhonda J.
Hess Douglas
Rapistan Systems Advertising Corp.
Van Dyke Gardner, Linn & Burkhart, LLP
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