Universal motor speed control circuits

Claim 2

In a speed control for a fractional horsepower universal motor having an armature and stator, the combination of a plurality of cowound field coils of different impedances on the stator of the motor, a second switch having a movable conductor between two of the coils to connect the coils in series between one side of a power source and the motor armature, a connection between the two coils including a first switch having a movable conductor to shunt one of the coils and said second switch, a connection between the two coils including a third switch having a movable conductor to shunt the other of the coils and said second switch, a multiposition switch control means interengaging said switch conductors, and selective manual means for moving said switch control means to one of its positions to close said first and third switch conductors and open said second switch conductor concurrently.

Claim 3

The combination called for in claim 1 in which said manual means moves said switch control means to a second position to open said first and third switch conductors and close said second switch conductor concurrently.

Claim 4

The combination called for in claim 2 in which said manual means moves said switch control means to a third position to close the first switch conductor and open said second and third switch conductors concurrently.

Claim 5

The combination called for in claim 2 in which said manual means moves said control means to close the third switch conductor and open said first and second switch conductors concurrently.

Claim 6

The combination called for in claim 1 including a third field coil on the stator and a connection between one of the said two coils and said third coil including a fourth switch having a movable conductor engaged by said switch control means to connect the third coil in series with said two coils, a connector between said third coil and one of said two coils including a fifth switch having a movable conductor engaged by said switch control means to bridge said fourth switch and said third coil, and said switch control means controlling said fourth and fifth switch conductors to open one and close the other of said fourth and fifth switches concurrently.

Claim 7

The combination called for in claim 5 in which said fifth switch is in series with one of the first two mentioned connections.

Claim 8

The combination called for in claim 5 including a connection between the other one of said two coils and said third coil and including a sixth switch having a movable conductor engaged by said switch control means to shunt said other one of said two coils and said fourth switch.

Claim 9

The combination called for in claim 7 in which the conductor of said sixth switch is in series with one of the first two mentioned connections.

Claim 10

The combination called for in claim 1 in which the armature and said field coils are connected in series relation with one side of a source of power and including a third field coil, means connecting the armature between one of the ends of the third coil and one of the other coils, connections including fourth and fifth switches having conductors independently connecting the armature and the other end of said third coil respectively in series with the other side of said source of power, and means controlling said fourth and fifth switch conductors to open one while closing the other of said fourth and fifth switches concurrently.

Claim 11

The combination called for in claim 9 in which said switch control means includes another manual means actuating said means controlling the fourth and fifth switches to close the conductors of said fifth switch concurrently with said second and third switches and opening the conductors of said first and fourth switches.

Claim 12

The speed control called for in claim 1 in which said two coils are Electrically connected on one side of the armature and field coil winding are connected in series between the other side of the power source and the motor armature and whose impedance remains constant for a range of speeds, and said permutations of series and parallel connections energize the same number of field coil turns at a plurality of fixed speeds within said range of speeds.

Claim 13

The combination called for in claim 1 in which said switch conductors are rated only to carry the current consumed by said coils, switch means connected in series with said switches having a conductor rated to make and break as well as carry said consumed current, and said switch control means controlling said switches to close said switch conductors before closing said switch means conductor and to open said switch conductors while said switch means conductor is open.

Claim 14

The combination called for in claim 1 in which said switch control means moves all three switches to their open positions to deenergize the circuit.

Claim 15

The combination called for in claim 1 including a manually moved, normally held open switch bridging at least one of said switches and connected in series with at least one of said coils for energization of said motor.

Claim 16

The combination called for in claim 1 in which said switch control means includes a fourth switch and a current rectifier connected in parallel with each other and in series with said coils, dual manual switch actuators for said control means, one actuator opening the conductor of the fourth switch and the other closing the conductor of the fourth switch.

Claim 17

The combination called for in claim 1 in which said switch conductors are normally closed switch conductors.

Claim 18

The combination called for in claim 1 in which the plurality of field coils are cowound with their wires in parallel and of the same lengths.

Claim 19

In a speed control for a fractional horsepower universal motor the combination of a plurality of field coils on a stator electrically connected serially in a circuit including an armature magnetically coacting with said stator, an electrical connector between adjacent ends of the coils including a second switch having a movable conductor to connect them in series, an electrical connector interconnecting one of said adjacent ends of one coil to the other end of the other coil including a first switch having a movable conductor connecting said one coil in series with the armature, an electrical connector interconnecting the other one of the adjacent ends to the other end of said one coil including a third switch having a movable conductor connecting said other coil in series with the armature, a first manually actuated control means for actuating said conductors and independently movable between alternate positions to provide four permutation cooperatively, said control means alternately closing the first and third switch conductors while opening the second switch conductor to connect said coils in parallel in one position and opening the first and third switch conductors while closing said second switch conductor to connect the coils in series in the alternate position, a second manually actuated control means coordinated with the movement of said first control means alternately to open said third conductor in one position and to close said third switch conductor in its other position when said first switch conductor is closed to connect said coils in said parallel relationship, and alternately to open said second switch in one position and close said second switch conductor in its other position when said first and third switch conductors are open to connect said coils in said series connection with the armature.

Claim 20

In a speed control for a fractional horsepower universal motor the combination of a plurality of field coils on a stator electrically connected serially in a circuit including an armature magnetically coacting with said stator, an electrical connector between adjacent ends of the coils including a second switch having a movable conductor to connect them in series, an electrical connector interconnecting one of said adjacent ends of one coil to the other end of the other coil including a first switch having a movable conductor connecting said one coil in series with the armature, an electrical connector interconnecting the other one of the adjacent ends to the other end of said one coil including a third switch having a movable conductor connecting said other coil in series with the armature, a first manually actuated control means for actuating said conductors and independently movable between alternate positions to provide four permutation cooperatively, said control means alternately closing the first and third switch conductors while opening the second switch conductor to connect said coils in parallel in one position and opening the first and third switch conductors while closing said second switch conductor to connect the coils in series in the alternate position, a second manually actuated control means coordinated with the movement of said first control means alternately to open said third conductor in one position and to close said third switch conductor in its other position when said first switch conductor is closed to connect said coils in said parallel relationship, and alternately to open said second switch in one position and close said second switch conductor in its other position when said first and third switch conductors are open to connect said coils in said series connection with the armature.

Claim 21

The combination called for in claim 18 in which one of said first and third connectors is opened by movement of one of the control means to OFF positions, and resilient means including manual means actuating one of said control means to close at least one of Said switch conductors momentarily.

Claim 22

The combination called for in claim 19 including a jogging switch means shunting one of said open switch conductors.

Claim 23

In a speed control for a fractional horsepower universal motor powered by alternating electrical current having an armature and stator, the combination of a plurality of field coils of different impedances on the stator serially connected in the motor circuit with the armature, a switch having a normally closed movable conductor in the serial connection to open the connection between two of said coils, a first switch means having a normally closed movable conductor bridging one of said coils and said switch, a second switch means having a normally closed movable conductor bridging another of said coils and said switch, a multiposition permutation switch control mean selectively opening said switch conductor in one position to leave the two coils connected in parallel to open said switch conductor, and either one of the switch means conductors for one coil in either one of two other positions, to leave the other coil individually in series with said armature, and to open both of said switch means conductors in another position to leave the coil serially connected in the motor circuit.

Claim 24

In a speed control for a fractional horsepower universal motor powered by alternating electrical current having an armature and stator, the combination of a plurality of field coils of different impedances on the stator serially connected in the motor circuit with the armature, a switch having a normally closed movable conductor in the serial connection to open the connection between two of said coils, a first switch means having a normally closed movable conductor bridging one of said coils and said switch, a second switch means having a normally closed movable conductor bridging another of said coils and said switch, a multiposition permutation switch control mean selectively opening said switch conductor in one position to leave the two coils connected in parallel to open said switch conductor, and either one of the switch means conductors for one coil in either one of two other positions, to leave the other coil individually in series with said armature, and to open both of said switch means conductors in another position to leave the coil serially connected in the motor circuit.

Claim 25

The combination called for in claim 21 including parallel connected current rectifier and third switch means having a normally closed conductor connected in series with at least one of said coils, two selective manual means independently actuating said switch control means, one of said manual means opening said third switch means conductor and the other manual means releasing said third switch means for closure thereof.

Claim 26

A speed control system for a universal electric motor connectable across a source of alternating current comprising: an armature, a plurality of field coils of differing impedances disposed on one side of the armature, first selective switch means to connect the field coils in series between the armature and one side of said source, second selective switch means to connect like ends of each coil independently to said one side of said source for connecting at least two of said coils in parallel, connector means having connections connecting the other ends of said coils separately and to the armature and including switches in at least two of said connections for selecting the coils that will be connected in parallel between said armature and said one side of said source.

Claim 27

A speed control system for a universal electric motor connectable across a source of alternating current comprising: an armature, a plurality of field coils of differing impedances disposed on one side of the armature, first selective switch means to connect the field coils in series between the armature and one side of said source, second selective switch means to connect like ends of each coil independently to said one side of said source for connecting at least two of said coils in parallel, connector means having connections connecting the other ends of said coils separately and to the armature and including switches in at least two of said connections for selecting the coils that will be connected in parallel between said armature and said one side of said source.