US3708696A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Zero voltage switch means for control of electric load circuit
Assignee: Robertshaw US Holding Corp
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Filing: 1971-01-28
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Granted: 1973-01-02
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Expires: 1991-01-28
Abstract
Abstract Four forms of the invention are shown and each comprises a zero voltage switching means for an AC electric load circuit having gate controlled semiconductors which are triggered in response to voltages in a condition sensitive bridge network connected in the AC power source for the load circuit. The network is shunted out of the power source circuit upon changes in power source voltage from zero in power source half cycles applied to the network whereby the components of the network are subjected only to relatively low voltages and during a brief portion of the half cycle. In one form of the invention, a resistance in the bridge network is heated in response to energization of the load circuit and tends to cause cycling of the switching means for accurate control of the load.
Inventors
- 👤 J Lorenz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:18
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/13; H03K17/136; G; G05; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1909; G05D23/1927; G05D23/20; G05D23/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
218 words
Control means for an electric load including an AC power supply for said load providing voltages alternating in polarity relative to a reference voltage, a first gate controlled switching means in circuit with said power supply and said load and operative to complete an energizing circuit for said load in response to a given triggering voltage applied to a gate thereof, a triggering circuit for the gate of said switching means connected with said AC power supply and including a condition responsive resistance element, a second gate controlled switching means connected with said AC power supply and adapted to form a shunt circuit around said triggering circuit when said second gate controlled switching means is conductive and thereby substantially limit current flow through said triggering circuit, and means To control the gate of said second gate controlled switching means to render said second switching means conductive in response to a given change in voltage value of said AC supply from said reference voltage during each alternation of said AC power supply, said triggering circuit adapted to effect a triggering voltage for said first gate controlled switching means in response to said changes in said AC voltage from said reference voltage and prior to attainment of said given voltage, depending upon the resistance of said condition responsive resistance element.
Claim 2
Dependent Claim
218 words
Control means for an electric load including an AC power supply for said load providing voltages alternating in polarity relative to a reference voltage, a first gate controlled switching means in circuit with said power supply and said load and operative to complete an energizing circuit for said load in response to a given triggering voltage applied to a gate thereof, a triggering circuit for the gate of said switching means connected with said AC power supply and including a condition responsive resistance element, a second gate controlled switching means connected with said AC power supply and adapted to form a shunt circuit around said triggering circuit when said second gate controlled switching means is conductive and thereby substantially limit current flow through said triggering circuit, and means To control the gate of said second gate controlled switching means to render said second switching means conductive in response to a given change in voltage value of said AC supply from said reference voltage during each alternation of said AC power supply, said triggering circuit adapted to effect a triggering voltage for said first gate controlled switching means in response to said changes in said AC voltage from said reference voltage and prior to attainment of said given voltage, depending upon the resistance of said condition responsive resistance element.
Claim 3
Dependent Claim
65 words
Control means as defined in claim 1 further characterized by said first gate controlled switching means comprising a triac in series with said load, said triggering circuit comprising a differential amplifier and an SCR coupled to one output circuit of said differential amplifier, and said means to control the gate of said second gate controlled switching means comprising another output circuit of said differential amplifier.
Claim 4
Dependent Claim
244 words
Control means for an electric load including an AC power supply for said load providing voltages alternating in polarity relative to a reference voltage, a first gate controlled switching means in circuit with said power supply and said load and operative to complete an energizing circuit for said load in response to a given triggering voltage applied to the gate thereof, triggering circuit means to control the gate of said switching means and connected with said AC power supply, means for shunting said triggering circuit means comprising a second gate controlled switching means for effecting current flow through said shunting means when said second gate controlled switching means is conductive and thereby substantially limit current flow through said triggering circuit, said triggering circuit means controlling the gate of said second gate controlled switching means and operable to render said second gate controlled switching means conductive, said triggering circuit means operative in response to a relatively small change in voltage value of said AC supply from said reference voltage to render one or the other of said switching means conductive during each alternation of said AC power supply, and a condition responsive impedance element in said triggering circuit operable to vary the triggering voltage at the gate of one of said gate controlled switching means to selectively cause one of said switching means to conduct prior to conduction of the other of said switching means, depending upon the impedance of said condition responsive impedance element.
Claim 5
Dependent Claim
244 words
Control means for an electric load including an AC power supply for said load providing voltages alternating in polarity relative to a reference voltage, a first gate controlled switching means in circuit with said power supply and said load and operative to complete an energizing circuit for said load in response to a given triggering voltage applied to the gate thereof, triggering circuit means to control the gate of said switching means and connected with said AC power supply, means for shunting said triggering circuit means comprising a second gate controlled switching means for effecting current flow through said shunting means when said second gate controlled switching means is conductive and thereby substantially limit current flow through said triggering circuit, said triggering circuit means controlling the gate of said second gate controlled switching means and operable to render said second gate controlled switching means conductive, said triggering circuit means operative in response to a relatively small change in voltage value of said AC supply from said reference voltage to render one or the other of said switching means conductive during each alternation of said AC power supply, and a condition responsive impedance element in said triggering circuit operable to vary the triggering voltage at the gate of one of said gate controlled switching means to selectively cause one of said switching means to conduct prior to conduction of the other of said switching means, depending upon the impedance of said condition responsive impedance element.
Claim 6
Dependent Claim
55 words
Control means as defined in claim 3 further characterized by said triggering circuit means comprising first and second voltage divider circuits, said first voltage divider circuit comprising said condition responsive impedance element and having an output which is dependent on the resistance of said element, and said second voltage divider circuit comprising substantially fixed impedances.
Claim 7
Dependent Claim
31 words
Control means as defined in claim 3 further characterized by said condition responsive impedance element operatable to vary the triggering voltage at the gate of said second gate controlled switching means.
Claim 8
Dependent Claim
30 words
Control means as defined in claim 4 further characterized by the output of said first voltage divider circuit operable to control the firing of said second gate controlled switching means.
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) | 1976-01-02 | 1976-07-03 | 1977-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-02 | 1980-07-03 | 1981-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-02 | 1984-07-03 | 1985-01-02 | $7700.00 | Window Closed / Lapsed |