Patent ID: 7080824
Filing Date: 2006-07-25
Classification: B66D

Abstract:
1. A chain motor drive controller for a chain hoist having a casing with a bidirectional chain drive motor having a chain drive shaft located within said casing comprising: a position encoder including a position sensor also located within said chain hoist casing, a direct mechanical drive coupling from said chain drive shaft formed as a pulley and belt drive system to transmit rotary motion from said chain drive shaft directly to said position sensor also located within said casing, and a tracking controller also located within said casing and coupled to receive digitized electrical position outputs generated by said position sensor in response to rotation of said chain drive shaft and to provide drive outputs that accelerate rotation of said chain drive shaft upon movement of said chain drive shaft from a stopped condition to a rotating condition and which decelerate rotation of said chain drive shaft as said position outputs from said position sensor approach an externally determined destination position, further comprising an alternating current drive controller interposed between said chain drive motor and said tracking controller, and a digital-to-analog converter for transforming encoded motor driving signals from said tracking controller from a digital form to an analog form as motor command signals to which said alternating current drive controller responds, and a motor stabilization circuit receiving said position outputs from said position sensor and destination inputs from an external source, and said motor stabilization circuit coupled directly to said alternating current drive controller and overrides said tracking controller only when said position outputs match said destination inputs.