Motor speed control system

Claim 2

A direct current motor control system, comprising: a. A series-wound direct current motor including a field winding and an armature having a pair of terminals.

Claim 3

One terminal of said armature being connected to said field winding and the second terminal of said armature being connected to ground; b. a diode connected in parallel with said field winding and said armature; c. an external control unit, including a direct current voltage source of constant amplitude and means for varying the magnitude of said voltage source; d. a drive circuit directly connected to said voltage source of said external control unit and to said field winding of said direct current motor to aperiodically provide a constant amplitude voltage signal thereto; e. a current-limiting and voltage-sensing circuit connected to said drive circuit and said voltage source of said external control unit, said current-limiting and voltage-sensing circuit being responsive to said means for varying the magnitude of said voltage source of said external control unit to activate said drive circuit to apply said constant amplitude voltage signal to said motor and responsive to said drive circuit to deactivate said drive circuit and remove said signal from said motor when the current level of said constant amplitude signal to said motor reaches a predetermined level; and f. a back electromotive force detector connected to said current-limiting and voltage-sensing circuit, said drive circuit and said field winding and diode, said back electromotive force detector, being responsive to the generated voltage of said motor to provide a back e.m.f. signal to maintain said current-limiting and voltage-sensing circuit in the state wherein said drive circuit is deactivated until such time as said generated voltage of said motor dissipates to a predetermined level whereby said current-limiting and voltagesensing circuit becomes operative to reactivate said drive circuit to reapply said constant amplitude signal to said motor until said current level of said constant amplitude signal again reaches said predetermined level.

Claim 4

One terminal of said armature being connected to said field winding and the second terminal of said armature being connected to ground; b. a diode connected in parallel with said field winding and said armature; c. an external control unit, including a direct current voltage source of constant amplitude and means for varying the magnitude of said voltage source; d. a drive circuit directly connected to said voltage source of said external control unit and to said field winding of said direct current motor to aperiodically provide a constant amplitude voltage signal thereto; e. a current-limiting and voltage-sensing circuit connected to said drive circuit and said voltage source of said external control unit, said current-limiting and voltage-sensing circuit being responsive to said means for varying the magnitude of said voltage source of said external control unit to activate said drive circuit to apply said constant amplitude voltage signal to said motor and responsive to said drive circuit to deactivate said drive circuit and remove said signal from said motor when the current level of said constant amplitude signal to said motor reaches a predetermined level; and f. a back electromotive force detector connected to said current-limiting and voltage-sensing circuit, said drive circuit and said field winding and diode, said back electromotive force detector, being responsive to the generated voltage of said motor to provide a back e.m.f. signal to maintain said current-limiting and voltage-sensing circuit in the state wherein said drive circuit is deactivated until such time as said generated voltage of said motor dissipates to a predetermined level whereby said current-limiting and voltagesensing circuit becomes operative to reactivate said drive circuit to reapply said constant amplitude signal to said motor until said current level of said constant amplitude signal again reaches said predetermined level.

Claim 5

A device according to claim 1 wherein said means for varying the magnitude of said voltage source comprises a mechanical means and a potentiometer for a varying the bias voltage applied to said current-limiting and voltage-sensing circuit.

Claim 6

A device according to claim 1 wherein said drive circuit comprises a saturated Darlington drive consisting of at least two power transistors in parallel.

Claim 7

A device according to claim 3 wherein said current-limiting and voltage-sensing circuit is responsive to said means for varying the magnitude of said voltage source to direct an energizing signal to said drive circuit to apply said voltage source to said motor and responsive to the current level of said signal applied to said motor by said drive circuit to deenergize said drive circuit.

Claim 8

A device according to claim 1 wherein said back electromotive force detector comprises a transistor having a base electrode, a collector electrode and an emitter electrode, said emitter electrode being connected to said drive circuit and said fieldwinding, said collector electrode being connected to said current-limiting and voltage-sensing circuit and said drive circuit, and said base electrode being connected to said emitter electrode by a diode, whereby said back electromotive force detector is effective to maintain said current-limiting and voltage-sensing circuit and said drive circuit in such condition to remove said constant amplitude signal from said motor until the generated voltage of said motor dissipates to a predetermined level.