Patent US3724433A successfully refreshed from Google Patents.
US3724433A
Expired / Lapsed
US
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Engine governor system with signal-loss protection and controlled oscillator circuit suitable for use therein
Assignee: Ambac Industries Inc
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Filing: 1971-08-13
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Granted: 1973-04-03
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Expires: 1991-08-13
Abstract
Abstract A controlled oscillator circuit which, in the absence of an input alternating signal, operates in a free-running manner to produce square-wave output signals at a predetermined frequency, and which responds to input alternating signals of a lower frequency to produce output square-waves at said lower frequency. When used in an engine-speed control system, the input alternating signal is a pickup signal representative of engine speed, and the square-wave output is applied to a phase-lockedloop type of frequency detector, the output of which varies the fuel control for the engine in the sense to accomplish the desired control. Should a loss of input alternating signal from the engine pickup device occur while the engine is operating, the controlled oscillator will nevertheless produce output square waves at a relatively high frequency to operate the frequency detector and reduce the engine power or completely shut it down, thereby avoiding erratic operation or ''''runaway'''' of the engine should the input alternating signal disappear. The controlled oscillator circuit preferably comprises a differential operational amplifier having a relatively long time-constant negative-feedback circuit and a relatively short time-constant positive feedback circuit providing two alternate astable states for producing square waves during free running, the input alternating signal being applied to a control input electrode of the operational amplifier to cause it to stay in each of its alternate astable states for a time equal to about one-half cycle of the input wave and to operate in synchronism with the input alternating signal.
Inventors
- 👤 J Voss
- 👤 W Ferry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:50
CPC Classifications
F; F02; F02D; F02D31/00; F02D31/001; F02D31/007; H; H02; H02P; H02P23/00; H02P23/16
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
274 words
In an engine speed control system comprising means responsive to operation of said engine for producing an alternating signal having a frequency proportional to the speed of operation of said engine, frequency-sensing means responsive to an input signal thereto for producing a control signal which changes in one direction when the frequency of said input signal increases and in the opposite direction when said frequency of said input signal decreases, means responsive to said alternating signal for supplying input signal to said frequency-sensing means, engine power control means for said engine, and electrical means responsive to said control signal for operating said engine power control means to control the speed of said engine and to hold said speed within a predetermined range, said system being such as to permit the speed of said engine to change uncontrolledly if the magnitude of said input signal to said frequency-sensing means becomes smaller than a predetermined value, the improvement wherein: said means responsive to said alternating signal for supplying input signal to said frequency-sensing means comprising an oscillator circuit having control terminals supplied with said alternating signal; said oscillator circuit operating, when said alternating signal is of less than a predetermined level, as a free-running oscillator to supply said input signal to said frequency-sensing means at a frequency higher than the maximum frequency of said alternating signal, but controlled by said alternating signal when it is above said predetermined level to supply said input signal to said frequency-sensing means at the same frequency as said alternating signal, whereby said engine speed is prevented from changing uncontrolledly when said alternating signal is of less than said predetermined level.
Claim 2
Dependent Claim
274 words
In an engine speed control system comprising means responsive to operation of said engine for producing an alternating signal having a frequency proportional to the speed of operation of said engine, frequency-sensing means responsive to an input signal thereto for producing a control signal which changes in one direction when the frequency of said input signal increases and in the opposite direction when said frequency of said input signal decreases, means responsive to said alternating signal for supplying input signal to said frequency-sensing means, engine power control means for said engine, and electrical means responsive to said control signal for operating said engine power control means to control the speed of said engine and to hold said speed within a predetermined range, said system being such as to permit the speed of said engine to change uncontrolledly if the magnitude of said input signal to said frequency-sensing means becomes smaller than a predetermined value, the improvement wherein: said means responsive to said alternating signal for supplying input signal to said frequency-sensing means comprising an oscillator circuit having control terminals supplied with said alternating signal; said oscillator circuit operating, when said alternating signal is of less than a predetermined level, as a free-running oscillator to supply said input signal to said frequency-sensing means at a frequency higher than the maximum frequency of said alternating signal, but controlled by said alternating signal when it is above said predetermined level to supply said input signal to said frequency-sensing means at the same frequency as said alternating signal, whereby said engine speed is prevented from changing uncontrolledly when said alternating signal is of less than said predetermined level.
Claim 3
Dependent Claim
33 words
Apparatus according to claim 1, in which said system is responsive to said higher frequency of said oscillator circuit, produced when it is free-running, to reduce said engine power to a low value.
Claim 4
Dependent Claim
25 words
Apparatus in accordance with claim 2, in which said system is responsive to the absence of said input signal to increase said engine speed uncontrolledly.
Claim 5
Dependent Claim
28 words
Apparatus according to claim 1, in which said oscillator circuit is operative to produce a substantially square wave both when free-running and when controlled by said alternating signal.
Claim 6
Dependent Claim
100 words
Apparatus in accordance with claim 4, in which said oscillator circuit comprises an amplifying device, a relatively-longer time constant negative feedback circuit, and a relatively-shorter time constant positive feedback circuit for said amplifying device, to provide two alternate stable states therefor; said alternating signal being applied to the input terminals of said amplifying device to maintain said device alternately in one of said states for a time equal to the duration of one half-cycle of said alternating signal and then in the other of said states for a time equal to the duration of one half-cycle of said alternating signal.
Claim 7
Dependent Claim
70 words
Apparatus in accordance with claim 5, in which said amplifying device is an operational amplifier having a pair of differential input terminals, said alternating signal being applied to the inverting input terminal of said device, said positive feedback circuit being connected between the output terminal of said operational amplifier and the non-inverting input terminal thereof, said negative feedback circuit being connected between said output terminal and said inverting input terminal.
Claim 8
Dependent Claim
22 words
Apparatus in accordance with claim 6, in which said positive feedback circuit comprises the series combination of resistor means and capacitor means.
Claim 9
Dependent Claim
41 words
Apparatus in accordance with claim 6, in which said negative feedback path comprises first and second resistance means connected in series between said output terminal and said inverting input terminal, and capacitive means connected effectively in parallel across said input terminals.
Claim 10
Dependent Claim
265 words
In an engine speed control system comprising means responsive to operation of said engine for producing an alternating signal having a frequency proportiOnal to the speed of operation of said engine, frequency-sensing means responsive to an input signal thereto for producing a control signal which changes in one direction when the frequency of said input signal increases and in the opposite direction when said frequency of said input signal decreases, means responsive to said alternating signal for supplying input signal to said frequency-sensing means, engine power control means for said engine, and electrical means responsive to said control signal for operating said engine power control means to control the speed of said engine, said system being such as to permit the speed of said engine to change uncontrolledly if the magnitude of said input signal to said frequency-sensing means becomes smaller than a predetermined value, the improvement wherein: said means responsive to said alternating signal for supplying input signal to said frequency-sensing means comprises an oscillator circuit having control terminals supplied with said alternating signal; said oscillator circuit operating, when said alternating signal is of less than a predetermined level, as a free-running oscillator to supply said input signal to said frequency-sensing means at a frequency higher than the maximum frequency of said alternating signal, but controlled by said alternating signal when it is above said predetermined level to supply said input signal to said frequency-sensing means at the same frequency as said alternating signal, whereby said engine speed is prevented from changing uncontrolledly when said alternating signal is of less than said predetermined level.
Claim 11
Dependent Claim
265 words
In an engine speed control system comprising means responsive to operation of said engine for producing an alternating signal having a frequency proportiOnal to the speed of operation of said engine, frequency-sensing means responsive to an input signal thereto for producing a control signal which changes in one direction when the frequency of said input signal increases and in the opposite direction when said frequency of said input signal decreases, means responsive to said alternating signal for supplying input signal to said frequency-sensing means, engine power control means for said engine, and electrical means responsive to said control signal for operating said engine power control means to control the speed of said engine, said system being such as to permit the speed of said engine to change uncontrolledly if the magnitude of said input signal to said frequency-sensing means becomes smaller than a predetermined value, the improvement wherein: said means responsive to said alternating signal for supplying input signal to said frequency-sensing means comprises an oscillator circuit having control terminals supplied with said alternating signal; said oscillator circuit operating, when said alternating signal is of less than a predetermined level, as a free-running oscillator to supply said input signal to said frequency-sensing means at a frequency higher than the maximum frequency of said alternating signal, but controlled by said alternating signal when it is above said predetermined level to supply said input signal to said frequency-sensing means at the same frequency as said alternating signal, whereby said engine speed is prevented from changing uncontrolledly when said alternating signal is of less than said predetermined level.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |