Anti-plug reversing module
AssigneeKB Electronics, Inc.
InventorsAbraham Saganovsky, William W. Chester
Life of this patent
Estimating the term…
Abstract
An anti-plug reversing circuit for use with a variable speed D.C. motor which provides safe and fast motor reversing with dynamic braking. The circuit, by sensing counter-EMF, prevents the premature application of a voltage of opposite (reversing) polarity until the motor armature has come to a full stop. The circuit advantageously utilizes a three-wire control input, is low cost, easily manufactured and applicable for use with low cost D.C. motors.
Claims6
A circuit for reversing the direction of rotation of a D.C. motor comprising;
- relay means, having a deenergized state and an energized state, for reversing the direction of current flow through the D.C. motor armature,
- a three position, three wire, switch having a forward position, a reverse position and a motor braking position, each switch position corresponding to a motor operation,
- means responsive to said switch being moved from said forward position to said reverse position while said D.C. motor is rotating in a forward direction, for removing motor driving voltage from said D.C. motor and for sensing motor counter-EMF to determine when said D.C. motor has essentially ceased rotation, and
- means responsive to said means for sensing motor counter-EMF for operating said relay means to reverse the direction of current flow through the D.C. motor armature at a point at which motor rotation has essentially ceased.
A circuit in accordance with claim 2, wherein said removing and sensing means is also responsive to said switch when said switch means is moved from said reverse direction to said forward direction.
Dependencies are inferred from the claim text.