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US3666973A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solid state electronic thermostat
Assignee: Control Design Inc
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Filing: 1970-08-19
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Granted: 1972-05-30
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Expires: 1990-08-19
Abstract
Abstract An apparatus for controlling the temperature of a device such as an oven in which a resistance having a positive temperature coefficient of resistance is incorporated in one leg of a bridge and is used to detect the temperature to be controlled. The bridge is energized by an alternating voltage and any unbalance appears across output terminals which are connected respectively to the bases of a first and a second transistor also energized with the same alternating voltage. The emitters of the transistors are connected together and through a common resistance so that the initiation of current flow through one transistor will inhibit current flow through the other. Flow of current through the second transistor triggers a silicon control rectifier which in turn controls a valve which supplies fuel to a burner in the oven. The voltage supplied to the bridge leads the voltage on the control rectifier so that it is always triggered at the beginning of its conducting half cycle. A third transistor is interposed between the second transistor and the silicon control rectifier. The changes in the response of the third transistor to its ambient temperature is compensated for in one of a number of ways. One is to have an ambient temperature sensitive resistance in the leg of the bridge diagonally opposite the first leg in which the first temperature sensitive resistance is placed. A second arrangement is to insert an ambient temperature sensitive diode in a leg adjacent to the first leg. A third arrangement is to insert an ambient temperature sensitive diode across the base and emitter of the third transistor. A delay circuit is provided for charging a condensor to delay the operation of the second transistor, the charge of said condensor being permitted to build up upon the initiation of current through the first transistor.
Inventors
- 👤 William H Hulsman Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 21:55
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G05D23/1906; G05D23/1909; G05D23/1927
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
259 words
In a temperature responsive control apparatus which includes a bRidge having two diagonally opposed input terminals, two diagonally opposed output terminals and first means responsive to the temperature to be controlled in one leg of said bridge: a. second means for supplying alternating power to said input terminals; b. first and second solid state electronic control devices each having a control element, said control elements being connected respectively to said output terminals; c. third means for supplying alternating power, of substantially the same phase as that supplied to said input terminals, to said control devices; d. fourth means common to said control devices for inhibiting the flow of current through said second control device in response to initiation of current flow through said first control device and for inhibiting the flow of current through said first control device responsive to initiation of current flow through said second control device; e. a controlled rectifier; f. means for supplying alternating power to said controlled rectifier, said alternating power lagging in phase with respect to the alternating power supplied to said input terminals; g. means responsive to flow of current through said second control device for initiating current flow through said rectifier; h. and means responsive to said last named current flow for controlling said temperature; whereby said phase relationship between the alternating power supplied to said controlled rectifier and the alternating power supplied to said bridge causes initiation of current flow through said controlled rectifier to occur early in the conducting half cycle of alternating power supplied to said controlled rectifier.
Claim 2
Dependent Claim
259 words
In a temperature responsive control apparatus which includes a bRidge having two diagonally opposed input terminals, two diagonally opposed output terminals and first means responsive to the temperature to be controlled in one leg of said bridge: a. second means for supplying alternating power to said input terminals; b. first and second solid state electronic control devices each having a control element, said control elements being connected respectively to said output terminals; c. third means for supplying alternating power, of substantially the same phase as that supplied to said input terminals, to said control devices; d. fourth means common to said control devices for inhibiting the flow of current through said second control device in response to initiation of current flow through said first control device and for inhibiting the flow of current through said first control device responsive to initiation of current flow through said second control device; e. a controlled rectifier; f. means for supplying alternating power to said controlled rectifier, said alternating power lagging in phase with respect to the alternating power supplied to said input terminals; g. means responsive to flow of current through said second control device for initiating current flow through said rectifier; h. and means responsive to said last named current flow for controlling said temperature; whereby said phase relationship between the alternating power supplied to said controlled rectifier and the alternating power supplied to said bridge causes initiation of current flow through said controlled rectifier to occur early in the conducting half cycle of alternating power supplied to said controlled rectifier.
Claim 3
Dependent Claim
220 words
In a temperature responsive control apparatus which includes a bridge having two diagonally opposed input terminals, two diagonally opposed output terminals and first means responsive to the temperature to be controlled in one leg of said bridge: a. second means for supplying alternating power to said input terminals; b. first and second solid state electronic control devices each having a control element, said control elements being connected respectively to said output terminals; c. third means for supplying alternating power, of substantially the same phase as that supplied to said input terminals, to said control devices; d. fourth means common to said control device for inhibiting the flow of current through said second control device in response to initiation of current flowing through said first control device and for inhibiting the flow of current through said first control device responsive to initiation of current flow through said second control device; e. a control circuit including a voltage responsive element to initiate flow of current to control said temperature in response to a predetermined voltage; f. a condenser; g. means for charging said condenser in response to current flow through said first control device; and h. means for connecting said condenser to said voltage responsive element in a direction to delay the application of said predetermined voltage to said voltage responsive element.
Claim 4
Dependent Claim
220 words
In a temperature responsive control apparatus which includes a bridge having two diagonally opposed input terminals, two diagonally opposed output terminals and first means responsive to the temperature to be controlled in one leg of said bridge: a. second means for supplying alternating power to said input terminals; b. first and second solid state electronic control devices each having a control element, said control elements being connected respectively to said output terminals; c. third means for supplying alternating power, of substantially the same phase as that supplied to said input terminals, to said control devices; d. fourth means common to said control device for inhibiting the flow of current through said second control device in response to initiation of current flowing through said first control device and for inhibiting the flow of current through said first control device responsive to initiation of current flow through said second control device; e. a control circuit including a voltage responsive element to initiate flow of current to control said temperature in response to a predetermined voltage; f. a condenser; g. means for charging said condenser in response to current flow through said first control device; and h. means for connecting said condenser to said voltage responsive element in a direction to delay the application of said predetermined voltage to said voltage responsive element.
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) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |