Patent US3629677A successfully refreshed from Google Patents.
US3629677A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Motor speed control circuit
Assignee: SCM-P&S Inc
•
Filing: 1969-11-03
•
Granted: 1971-12-21
•
Expires: 1989-11-03
Abstract
Abstract An improved circuit for precisely controlling the speed at which a motor rotates and for protecting the motor against excessive current drain. Pulses generated synchronously with rotation of the motor trigger a one-shot. The one-shot generates a nonsymmetrical square wave whose symmetry varies with the rotational speed of the motor. In one embodiment, an integrating circuit then converts this nonsymmetrical square wave into a sawtooth or triangular waveform that includes a DC component proportional in magnitude to the motor rotation speed. This waveform is fed into one input of a differential amplifier. The amplifier generates a continuous output, a pulse width modulated rectangular wave output, or no output, depending upon whether the motor is running below the proper speed, approximately the proper speed, or overspeed. This output is fed to a switching-type current regulator connected in series with the motor.
Inventors
- 👤 Gary L Means
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:56
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/0833; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/29; H02P7/2913
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
154 words
A motor speed control circuit comprising: means for generating a first signal whose frequency is proportional to the motor speed of rotation; a one-shot multivibrator having said first signal as an input and having an output at which an output signal containing periodic pulses appears each time said first sIgnal fluctuates; integrating or low-pass filtering means for partially integrating or filtering the output signal of the multivibrator to produce a composite signal including a direct current component proportional to the average DC value of the periodic pulses and having a short enough time-constant so that a substantial triangular component appears in the composite signal; a differential amplifier having one input connected to the composite signal generated by said integrating means, having a second input connected to a reference potential, and having an output; and a switching circuit having an input connected to said differential amplifier output and having an output connected to the motor.
Claim 2
Dependent Claim
154 words
A motor speed control circuit comprising: means for generating a first signal whose frequency is proportional to the motor speed of rotation; a one-shot multivibrator having said first signal as an input and having an output at which an output signal containing periodic pulses appears each time said first sIgnal fluctuates; integrating or low-pass filtering means for partially integrating or filtering the output signal of the multivibrator to produce a composite signal including a direct current component proportional to the average DC value of the periodic pulses and having a short enough time-constant so that a substantial triangular component appears in the composite signal; a differential amplifier having one input connected to the composite signal generated by said integrating means, having a second input connected to a reference potential, and having an output; and a switching circuit having an input connected to said differential amplifier output and having an output connected to the motor.
Claim 3
Dependent Claim
65 words
The motor speed control circuit in accordance with claim 1 wherein the signal generating means comprises: an amplifier having an input and having an output at which said first signal appears; a coil connected to the input of said amplifier; and a rotating device affixed to the shaft of said motor, said device containing spaced magnetic elements about its periphery and positioned adjacent said coil.
Claim 4
Dependent Claim
36 words
A motor speed control circuit in accordance with claim 1 wherein the one-shot generates a continuous, unbroken output signal whenever the fluctuations in said first signal are more closely spaced than the duration of said output.
Claim 5
Dependent Claim
62 words
A motor speed control circuit in accordance with claim 1 wherein the integrator comprises: an integrating capacitor having a first terminal connected to a reference potential and having a second terminal; a resistor connected between said second terminal of the integrating capacitor and a reference potential; and resistance means connecting the second terminal of said capacitor to the output of said multivibrator.
Claim 6
Dependent Claim
63 words
A motor speed control circuit in accordance with claim 1 wherein the integrator comprises: an integrating capacitor having a first terminal connected to a reference potential and having a second terminal; a current source connected between said second terminal of the integrating capacitor and a reference potential; and resistance means connecting the second terminal of said capacitor to the output of said multivibrator.
Claim 7
Dependent Claim
51 words
A motor speed control circuit in accordance with claim 1 wherein the differential amplifier has a noninverting input connected to the output of said integrator and an inverting input connected to the reference potential, and further includes a positive feedback circuit path connecting the differential amplifier output to the noninverting input.
Claim 8
Dependent Claim
19 words
A motor speed control circuit in accordance with claim 1 wherein the differential amplifier operates as a Schmitt trigger.
Claim 9
Dependent Claim
164 words
A motor speed control circuit comprising: means for producing a periodic signal that fluctuates at a rate proportional to the rotational velocity of the motor; pulse generating means for generating periodic pulses of fixed time duration each time the periodic signal fluctuates; integrating or low-pass filtering means for partially integrating or filtering the periodic pulses to produce a composite signal including a direct current component proportional to the average DC value of the periodic pulses and having a short enough time-constant so that a substantial triangular component appears in the composite signal; comparator means having an output for comparing the composite signal to a reference potential and for generating a motor control signal that is at a first level when the composite signal exceeds the reference potential and at a second level when the reference potential exceeds the composite signal; and switching means connected to the motor for supplying current to the motor only when the motor control signal is at a predetermined level.
Claim 10
Dependent Claim
164 words
A motor speed control circuit comprising: means for producing a periodic signal that fluctuates at a rate proportional to the rotational velocity of the motor; pulse generating means for generating periodic pulses of fixed time duration each time the periodic signal fluctuates; integrating or low-pass filtering means for partially integrating or filtering the periodic pulses to produce a composite signal including a direct current component proportional to the average DC value of the periodic pulses and having a short enough time-constant so that a substantial triangular component appears in the composite signal; comparator means having an output for comparing the composite signal to a reference potential and for generating a motor control signal that is at a first level when the composite signal exceeds the reference potential and at a second level when the reference potential exceeds the composite signal; and switching means connected to the motor for supplying current to the motor only when the motor control signal is at a predetermined level.
References Cited (Backward Citations)
US3231757A
Cited
US3234447A
Cited
US3260912A
Cited
US3223912A
Cited
US3409814A
Cited
US3411063A
Cited
US3437826A
Cited
US3508132A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |