Method and Apparatus for Sorting or Retrieving Items

Abstract

A method and apparatus are provided for sorting or retrieving items to/from a plurality of destinations areas. The items are loaded onto one of a plurality of independently controlled delivery vehicles. The delivery vehicles follow a track that guides the delivery vehicles to/from the destination areas, which are positioned along the track. Once at the appropriate destination area, an item is transferred between the delivery vehicle and the destination area.

What is claimed is: 
     
         1 . A method for storing and retrieving items in a material handling system having a first rack of storage locations and a second rack of storage locations spaced apart from the first rack to form an aisle between the first rack and the second rack and a vehicle path forming a vertical loop within the aisle, comprising the steps of:
 storing a plurality of containers in the storage locations in the first and second storage racks;   driving a plurality of vehicles along the vehicle path to retrieve containers from the storage locations;   conveying a first container outside the aisle between a transfer location located adjacent the vehicle path and a remote location that is remote from the aisle and the first and second racks;   driving a first of the plurality of vehicles within the aisle along the vehicle path to the transfer location;   loading the first container onto the first vehicle from the transfer location; and   driving the first vehicle and the first container away from the transfer location, comprising the step of driving the vehicle along the vehicle path within the aisle to a first of the storage locations within the first and second racks.   
     
     
         2 . The method of  claim 1  wherein the step of conveying a first container outside the conveyor comprises conveying the first container along a conveyor outside of the aisle. 
     
     
         3 . The method of  claim 1  wherein the step of conveying a first container comprises conveying the first container to the transfer location. 
     
     
         4 . The method of  claim 1  wherein the transfer location is within the first or second rack. 
     
     
         5 . The method of  claim 1  wherein the step of loading comprises driving a transfer mechanism on the first vehicle to pull the first container onto the first vehicle. 
     
     
         6 . The method of  claim 5  wherein the step of loading comprises driving the transfer mechanism into engagement with the first container. The method of  claim 1  comprising the step of driving a second one of the vehicles with a second one of the containers to the transfer location and conveying the item away from the transfer location. 
     
     
         8 . The method of claim  7  wherein the second container is one of the containers in one of the storage locations in the first or second rack and the method comprises the step of retrieving the second container from the first or second rack. 
     
     
         9 . The method of  claim 8  comprising the step of driving a conveyor to convey the second container from the second vehicle away from the aisle. 
     
     
         10 . The method of  claim 1  wherein the step of driving a plurality of vehicles comprises conveying the vehicles vertically and conveying the vehicles horizontally. 
     
     
         11 . The method of  claim 10  wherein the vehicles comprise drive elements that mesh with drive surfaces of a vertical track wherein the step of conveying the vehicles vertically comprises engaging the drive elements of the vehicles with the drive surfaces of the track and driving the drive elements of the vehicles. 
     
     
         12 . The method of  claim 1  comprising the step of stopping the first vehicle adjacent the transfer location. 
     
     
         13 . A material handling system, comprising:
 a first rack of storage locations configured to receive one or more containers;   a second rack of storage locations spaced apart from the first rack to form an aisle between the first rack and the second rack with a vehicle path forming a vertical loop within the aisle wherein the storage locations in the second rack are configured to receive one or more containers;   a plurality of vehicles operable within the aisle to deliver containers to the storage locations and retrieve containers from the storage locations wherein each vehicle comprises one or more wheels for driving the vehicle along the vehicle path and a rechargeable power storage element for powering operation of the vehicle;   a transfer location configured to receive one or more container, wherein the transfer location is positioned along the vehicle path;   wherein each vehicle comprises a transfer mechanism for transferring containers between the vehicles and the first and second racks and the transfer location   a conveyor communicating with the transfer location wherein the conveyor extends away from the transfer location so that the conveyor is operable to deliver containers to the transfer location from a location outside the first and second racks or to displace containers away from the transfer location to a location outside the first and second racks.   
     
     
         14 . The material handling system of  claim 13  comprising first and second horizontal tracks adjacent the first rack for guiding the delivery vehicles along the vehicle path wherein the first and second horizontal tracks are vertically spaced apart from one another. 
     
     
         15 . The material handling system of  claim 14  comprising third and fourth horizontal tracks adjacent the second rack for guiding the delivery vehicles along the vehicle path wherein the third and fourth horizontal track are vertically aligned with the first and second horizontal tracks. 
     
     
         16 . The material handling system of  claim 13  wherein the transfer location is within the first or second rack. 
     
     
         17 . The material handling system of  claim 13  wherein the transfer mechanism of each vehicle is configured to engage the containers to pull the containers onto the vehicle. 
     
     
         18 . The material handling system of  claim 13  wherein the vehicles comprise drive elements that mesh with drive surfaces of a vertical track wherein and the vehicles are operable to engage the drive elements with the drive surfaces of the track and drive the drive elements of the vehicles to drive the vehicles vertically within the aisle.