US4168516A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Precision speed switch control
Assignee: Woodward Controls Inc
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Filing: 1977-10-04
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Granted: 1979-09-18
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Expires: 1997-10-04
Abstract
Abstract A speed switch control comprising a subfractional permanent magnet AC generator generating an AC signal varying in amplitude with saft speed variations; the AC signal is rectified and compared with a regulated DC reference to generate first and second threshold signals indicative of shaft speeds over and under a critical value. A switch actuator circuit develops "on" and "off" switch actuator signals, from the threshold signals to actuate a two-terminal solid state switch between on and off conditions; the "off" signal is continuous but the "on" signal is a high-duty-cycle semi-continuous signal including brief recurring "off" intervals. A power storage/supply circuit, connected in parallel with the switch terminals, which recharges during switch "off" intervals, affords the power supply for the threshold and switch actuator circuits.
Inventors
- 👤 Melvin A. Lace
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:57
CPC Classifications
G; G01; G01R; G01R23/00; G01P; G01P1/00; G01P1/07; G01P1/08; G01P1/10; G01P1/103; G01P3/00; G01P3/42; G01P3/44; G01P3/46; G01P3/465
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
281 words
A two-terminal precision speed switch control actuated by changes in the rotational speed of a shaft and adaptable to operation over a broad speed range down to less than ten rpm comprising: a sub-fractional AC generator, connectible to a rotary shaft, for generating an AC signal having an amplitude which varies with changes in shaft speed; a threshold circuit, connected to the generator, for developing first and second threshold signals, one indicative of an AC signal input exceeding a given threshold amplitude corresponding to a critical shaft speed and the other indicative of an AC signal input below the threshold amplitude; a switch actuator circuit, coupled to the threshold circuit, for developing ON and OFF switch actuation signals corresponding to the first and second threshold signals, the OFF signal being a continuous DC signal and the ON signal being a semi-continuous DC signal of high duty cycle including brief recurring OFF intervals; a solid-state switching circuit, having two switch terminals connectible in series with an external power supply in an operating circuit for a controlled load and having an actuation input connected to the switch actuator circuit, actuatable to an "on" condition in which the impedance across the switch terminals is very low, in response to the ON switch actuation signal, and actuatable to an "off" condition in which the impedance across the switch terminals is very high, in response to the OFF switch actuation signal; and a power storage/supply circuit, connected in parallel with the switch terminals, affording a power supply for the threshold circuit and the switch actuator circuit, and including a storage device which is re-charged during intervals in which the switching circuit is in its "off" condition.
Claim 2
Dependent Claim
281 words
A two-terminal precision speed switch control actuated by changes in the rotational speed of a shaft and adaptable to operation over a broad speed range down to less than ten rpm comprising: a sub-fractional AC generator, connectible to a rotary shaft, for generating an AC signal having an amplitude which varies with changes in shaft speed; a threshold circuit, connected to the generator, for developing first and second threshold signals, one indicative of an AC signal input exceeding a given threshold amplitude corresponding to a critical shaft speed and the other indicative of an AC signal input below the threshold amplitude; a switch actuator circuit, coupled to the threshold circuit, for developing ON and OFF switch actuation signals corresponding to the first and second threshold signals, the OFF signal being a continuous DC signal and the ON signal being a semi-continuous DC signal of high duty cycle including brief recurring OFF intervals; a solid-state switching circuit, having two switch terminals connectible in series with an external power supply in an operating circuit for a controlled load and having an actuation input connected to the switch actuator circuit, actuatable to an "on" condition in which the impedance across the switch terminals is very low, in response to the ON switch actuation signal, and actuatable to an "off" condition in which the impedance across the switch terminals is very high, in response to the OFF switch actuation signal; and a power storage/supply circuit, connected in parallel with the switch terminals, affording a power supply for the threshold circuit and the switch actuator circuit, and including a storage device which is re-charged during intervals in which the switching circuit is in its "off" condition.
Claim 3
Dependent Claim
30 words
A speed switch control according to claim 1 in which the switch actuator circuit is a monostable trigger circuit having a duty cycle of the order of 95% or more.
Claim 4
Dependent Claim
35 words
A speed switch control according to claim 1 in which the switch actuator circuit comprises an amplifier responsive to the level of charge on a storage device comprising a part of the power storage/supply circuit.
Claim 5
Dependent Claim
76 words
A speed switch control according to claim 3 in which the switch actuator circuit comprises an operational amplifier having an inverting input and a non-inverting input, one input of the amplifier being connected to a voltage divider affording an input voltage proportional to the charge on the storage device in the power storage/supply circuit, the other input of the amplifier being connected to a clamp circuit affording an input voltage limited to a predetermined maximum value.
Claim 6
Dependent Claim
52 words
A speed switch control according to claim 4, in which the threshold circuit comprises an amplifier having its output connected to the one input of the actuator circuit amplifier in a circuit that maintains that one actuator circuit amplifier input at a reference level whenever one of the threshold signals is present.
Claim 7
Dependent Claim
90 words
A speed switch control according to claim 1 in which the power storage/supply circuit includes a voltage-regulated output, and in which the threshold circuit comprises an operational amplifier having an inverting input and a non-inverting input, with one amplifier input coupled to the generator through a rectifier circuit and the other amplifier input connected to the regulated output of the power storage/supply by a reference circuit, in which a change between normally-closed and normally-open operation for the switching circuit is effected by interchanging the input connections to that operational amplifier.
Claim 8
Dependent Claim
45 words
A speed switch control according to claim 6 in which the rectifier circuit in the threshold circuit includes a time delay circuit to delay a change in operating condition of the switching circuit upon deceleration of the generator to a speed below the critical speed.
Claim 9
Dependent Claim
34 words
A speed switch control according to claim 6 in which the rectifier circuit in the threshold circuit includes an adjustable impedance for varying the critical speed of the control over a broad speed range.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-09-17 | 1983-03-19 | 1983-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-17 | 1987-03-19 | 1987-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-17 | 1991-03-19 | 1991-09-18 | $7700.00 | Window Closed / Lapsed |