Motor control circuit

Claim 2

Apparatus for controlling the speed of a direct current motor comprising: a first direct voltage source; a direct current motor having an armature; current-sensing means for sensing current flow through said armature; current-passage means across said armature and capable of assuming a first state in which current is allowed to flow therethrough and a second state in which current is prevented from flowing therethrough; switching means connected to said current passage means and responsive to said current sensing means for causing said current passage means to assume its first state in response to the sensing of a first armature current flow condition and to assume its second state in response to the sensing of a second armature current flow condition; and a current control means coupled to the current passage means and including a current passage path connected serially with said armature and said current-sensing means across said first direct voltage source for controlling current flow through said armature in response to the state of said curreNt passage means.

Claim 3

Apparatus as claimed in claim 1 in which said switching means comprises bias means and a first transistor having its base-emitter circuit connected between said bias means and said current sensing means to cause said current passage means to assume one of its states when the armature current exceeds a preset value and to assume the other of its states when the armature current is less than said preset value.

Claim 4

Apparatus as claimed in claim 1 in which said bias means comprises diode means and a first resistor serially connected across said first direct voltage source.

Claim 5

Apparatus as claimed in claim 2 in which said current passage means comprises a second transistor having its emitter-collector circuit serially connected with a resistor across said armature and having its base connected to said first transistor to prevent current flow through said second transistor emitter-collector circuit when the armature current exceeds said preset value and to permit current flow through said second transistor when the armature current is less than said preset value.

Claim 6

Apparatus as claimed in claim 4 in which said current control means comprises: a. semiconductor means including a control element and including a current passage path coupling said first direct voltage source to said armature; and b. a variable direct voltage source coupled to said semiconductor means control element whereby current flow through said semiconductor means current passage path responds to variations in voltage at said semiconductor means control element.

Claim 7

Apparatus for controlling the speed of a direct current motor comprising: a first direct voltage source; a direct current motor having an armature; current-sensing means for sensing current flow through said armature; current control means including a current passage path connected serially with said armature and said current-sensing means across said first direct voltage source; current passage means across said armature and capable of assuming a first state in which current is allowed to flow therethrough and a second state in which current is prevented from flowing therethrough; and switching means including bias means and a first transistor having its base-emitter circuit connected between said bias means and said current-sensing means to cause said current passage means to assume one of its states when the armature current exceeds a preset value and to assume the other of its states when the armature current is less than said preset value.

Claim 8

Apparatus for controlling the speed of a direct current motor comprising: a first direct voltage source; a direct current motor having an armature; current-sensing means for sensing current flow through said armature; current control means including a current passage path connected serially with said armature and said current-sensing means across said first direct voltage source; current passage means across said armature and capable of assuming a first state in which current is allowed to flow therethrough and a second state in which current is prevented from flowing therethrough; and switching means including bias means and a first transistor having its base-emitter circuit connected between said bias means and said current-sensing means to cause said current passage means to assume one of its states when the armature current exceeds a preset value and to assume the other of its states when the armature current is less than said preset value.

Claim 9

Apparatus as claimed in claim 6 in which said bias means comprises diode means and a first resistor serially connected across said first direct voltage source.

Claim 10

Apparatus as claimed in claim 6 in which said current passage means comprises a second transistor having its emitter-collector circuit serially connected with a resistor across said armature and having its base connected to said first transistor to prevent current flow through said second transistor emitter-collector circuit when the armature current exceeds said preset value and to permit current flow through said second transistor when the armature current is less than said preset value.

Claim 11

Apparatus as claimed in claim 8 in which said current control means comprises: a. semiconductor means including a control element and including a current passage path coupling said first direct voltage source to said armature; and b. a variable direct voltage source coupled to said semiconductor means control element whereby current flow through said semiconductor means current passage path responds to variations in voltage at said semiconductor means control element.

Claim 12

Apparatus for controlling the speed of a direct current motor comprising: a. a first direct voltage source; b. a direct current motor having an armature; c. current sensing means for sensing current flow through said armature; d. first and second resistance means joined together for cUrrent flow serially therethrough; e. a variable direct voltage source; and f. control means for controlling armature current having a current path connected serially with said armature and said current sensing means across said first direct voltage source and having a control element coupled to said first and second resistance means; said armature, said control element and said first resistance means forming a first voltage loop; said variable direct voltage source, said current sensing means, said control element, and said second resistance means forming a second voltage loop; a voltage variation within one of said voltage loops causing a compensating variation in the current flowing serially through the two said resistance means to maintain the armature counter electromotive force substantially equal to the voltage from said variable direct voltage source.

Claim 13

Apparatus for controlling the speed of a direct current motor comprising: a. a first direct voltage source; b. a direct current motor having an armature; c. current sensing means for sensing current flow through said armature; d. first and second resistance means joined together for cUrrent flow serially therethrough; e. a variable direct voltage source; and f. control means for controlling armature current having a current path connected serially with said armature and said current sensing means across said first direct voltage source and having a control element coupled to said first and second resistance means; said armature, said control element and said first resistance means forming a first voltage loop; said variable direct voltage source, said current sensing means, said control element, and said second resistance means forming a second voltage loop; a voltage variation within one of said voltage loops causing a compensating variation in the current flowing serially through the two said resistance means to maintain the armature counter electromotive force substantially equal to the voltage from said variable direct voltage source.

Claim 14

Apparatus as claimed in claim 10 in which said control means comprises semiconductor means including a control member connected to the junction of said first and second resistance means and including a current passage path coupling said first direct voltage source to said armature.

Claim 15

Apparatus as claimed in claim 10 in which: a. said first and resistance passage means comprises first and second resistors serially joined together; b. said variable voltage source is serially connected with said first and second resistors across the serial combination of said armature and said current sensing means; and c. said control means comprises first transistor means having a collector-emitter circuit coupling said first direct voltage source to a first side of said armature and second transistor means having its collector coupled to the control element of said first transistor means, its emitter connected to a second side of said armature, and its control element connected to the junction of said first and second resistors.