Shaft speed control system comprising clutch and brake

Claim 2

In an electric drive having an output shaft, a driving motor and an intermediate electromagnetically actuated clutch and a brake in assembly connecting said motor to a utilization device, a control system for regulating the speed of said output shaft, comprising: shaft speed measuring means including means to generate an AC voltage signal of an amplitude which is a function of the actual speed of said output shaft; a power inverter means connected to the output of said means to generate and including means to convert the output signal of said means to generate into an output signal having a DC signal component proportional to the amplitude of the AC voltage and a pulsed DC voltage component superimposed thereon; an impedance-matching circuit connected to the output of said power inverter means; means to actuate said clutch through said impedance-matching circuit, when the output signal of said power inverter means falls below a first reference voltage, and to actuate said brake when the output signal of said power inverter means exceeds a second, higher, reference voltage.

Claim 3

A control system for use in a motor drive as claimed in claim 1, said speed-measuring means comprising a desired shaft-speed-presetting means to a first lower and a second higher reference value and means to alternately excite the winding of said clutch and the winding of said brake to maintain the speed preset on said presetting means.

Claim 4

The control system of claim 1 wherein the power inverter means comprises a full-wave rectifier having an input and an output, a parallel combination of a resistor and a capacitor connected to the rectifier output for smoothing pulsating DC voltage appearing at the output, the pulsating DC voltage being produced by biased full-wave rectification of the generated AC output from the measuring means.

Claim 5

The control system of claim 3 together with impedance-matching means connected between the power inverter means and both switch means to prevent undue loading of the power inverter means.

Claim 6

The control system of claim 3 together with adjusting means disposed in circuit between the speed-measuring means and the power inverter means for selecting a desired output shaft speed.

Claim 7

The system set forth in claim 5 wherein the adjusting means comprises a transformer having a primary coupled to the shaft-speed-measuring means and a secondary connected to the input of the rectifier, the airgap between the windings being adjustable to effect a variable coupling factor therebetween.

Claim 8

The system set forth in claim 6 wherein the first and second switch means are characterized by solid-state semiconductor devices having indefinite useful lives.

Claim 9

The system defined in claim 7 together with meAns for varying the bias on the semiconductor devices resulting in the establishment of the respective preselected reference voltages.

Claim 10

The system of claim 8 wherein the clutch and the brake include energizing input circuits connected in circuit with the first and second switch means which supply power thereto, and means connected to the windings of said clutch and brake for reducing the time constant of the input circuits.

Claim 11

The system set forth in claim 3 wherein the speed-measuring means comprises an inductive voltage regulator having a magnetic disc of multiple peripheral poles secured to the output shaft, and a stationary core positioned adjacent the disc, the core being characterized by an E-shaped cross section, the central leg of the core mounting a coil across which an AC voltage is induced as the disc rotates with the shaft, the two outer legs of the core being displaced from the central leg by an amount equal to two adjacent poles of the disc.

Claim 12

An electric drive for operating a utilization device comprising, a motor having an output shaft; an output drive shaft, an electromagnetic clutch-brake assembly interposingly connecting the drive shaft and the motor shaft; the utilization device being connected to the output shaft and deriving power therefrom; an electronic control system for regulating output shaft speed including shaft speed measuring means for generating AC voltage whose amplitude is a function of the actual speed of the output shaft; power inverter means responding to the measuring means for converting the generated AC output of the measuring means into an output signal having a DC voltage signal component substantially proportional to the amplitude of the AC voltage and a pulsed DC voltage component superimposed thereon; first switch means connected to the clutch for causing energization thereof in response to an output voltage dropping below a first preselected reference value; and second switch means connected to the brake for causing energization thereof in response to a second preselected reference value being higher than the first.

Claim 13

An electric drive for operating a utilization device comprising, a motor having an output shaft; an output drive shaft, an electromagnetic clutch-brake assembly interposingly connecting the drive shaft and the motor shaft; the utilization device being connected to the output shaft and deriving power therefrom; an electronic control system for regulating output shaft speed including shaft speed measuring means for generating AC voltage whose amplitude is a function of the actual speed of the output shaft; power inverter means responding to the measuring means for converting the generated AC output of the measuring means into an output signal having a DC voltage signal component substantially proportional to the amplitude of the AC voltage and a pulsed DC voltage component superimposed thereon; first switch means connected to the clutch for causing energization thereof in response to an output voltage dropping below a first preselected reference value; and second switch means connected to the brake for causing energization thereof in response to a second preselected reference value being higher than the first.

Claim 14

The system of claim 11 wherein the power inverter means comprises a full-wave rectifier having an input and an output, a parallel combination of a resistor and a capacitor connected to the rectifier output for smoothing pulsating DC voltage appearing at the output, the pulsating DC voltage being produced by biased full-wave rectification of the generated AC output from the measuring means.

Claim 15

The system of claim 12 together with impedance-matching means connected between the power inverter means and both switch means to prevent undue loading of the power inverter means.

Claim 16

The system of claim 12 together with adjusting means disposed in circuit between the speed-measuring means and the power inverter means for selecting a desired output shaft speed.

Claim 17

The system set forth in claim 14 wherein the adjusting means comprises a transformer having a primary coupled to the shaft-speed-measuring means and a secondary connected to the input of the rectifier, the airgap between the windings being adjustable to effect a variable coupling factor therebetween.

Claim 18

The system set forth in claim 15 wherein the first and second switch means are characterized by solid-state semiconductor devices having indefinite useful lives.

Claim 19

The system defined in claim 16 together with means for varying the bias on the semiconductor devices resulting in the establishment of the respective preselected reference voltages.

Claim 20

The system of claim 17 wherein the clutch and the brake include energizing input circuits connected in circuit with the first and second switch means which supply power thereto, and means connected to the windings of said clutch and brake for reducing the time constant of the input circuits.

Claim 21

The system set forth in claim 12 wherein the speed-measuring means comprises an inductive voltage regulator hAving a magnetic disc of multiple peripheral poles secured to the output shaft, and a stationary core positioned adjacent the disc, the core being characterized by an E-shaped cross section, the central leg of the core mounting a coil across which an AC voltage is induced as the disc rotates with the shaft, the two outer legs of the core being displaced from the central leg by an amount equal to two adjacent poles of the disc.