US3912906A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for electric heating system
Assignee: Robertshaw Controls Co
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Filing: 1974-04-24
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Granted: 1975-10-14
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Expires: 1994-04-24
Abstract
Abstract An electrical circuit for a heating system has a plurality of electrical resistance heating elements which are sequentially operated while a blower is maintained in operation when any of the heating elements are energized. The blower motor is operated by a controlled switch which has a control electrode connected to both a thermostat switch and to a device, such as a magnetic current sensing transformer, sensing energization of any of the electrical resistance heating elements.
Inventors
- 👤 Harold A Mcintosh
- 👤 Bradford N Hull
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 07:17
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/275; G05D23/1906; G05D23/1912
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
204 words
A circuit for an electrical heating system comprising first, second and third switches, control switch means for operating the first switch, said control switch means having a control electrode which when energized operates the control switch means, means for operating the second switch a predetermined duration after the operation of the first switch, means for operating the third switch a predetermined duration after the operation of the second switch, first and second heating elements connected to the respective second and third switches to be energized when the respective second and third switches are operated, fluid moving motor means operated by operation of the first switch for moving a fluid medium over the first and second heating elements, a thermostat having contacts which are closed at temperatures below a selected temperature and open at temperatures above the selected temperature, said contacts connected to the control electrode for energizing the control electrode when closed, and connected in series with the second switch operating means for sequentially terminating operation of the second switch operating means and the third switch operating means when open, and means sensing energization of any of the first and second heating elements and connected to the control electrode for energizing the control electrode.
Claim 2
Dependent Claim
204 words
A circuit for an electrical heating system comprising first, second and third switches, control switch means for operating the first switch, said control switch means having a control electrode which when energized operates the control switch means, means for operating the second switch a predetermined duration after the operation of the first switch, means for operating the third switch a predetermined duration after the operation of the second switch, first and second heating elements connected to the respective second and third switches to be energized when the respective second and third switches are operated, fluid moving motor means operated by operation of the first switch for moving a fluid medium over the first and second heating elements, a thermostat having contacts which are closed at temperatures below a selected temperature and open at temperatures above the selected temperature, said contacts connected to the control electrode for energizing the control electrode when closed, and connected in series with the second switch operating means for sequentially terminating operation of the second switch operating means and the third switch operating means when open, and means sensing energization of any of the first and second heating elements and connected to the control electrode for energizing the control electrode.
Claim 3
Dependent Claim
82 words
A circuit for a heating system as claimed in claim 1 wherein there are included first and second lines connected to said first and second heating elements for energizing the first and second heating elements, and the energizing means includes a ferro-magnetic core inductively coupled to said first and second lines, and a pick up coil wound on the magnetic core for energizing the pick up coil would on the magnetic core for energizing the control electrode of the control switch means.
Claim 4
Dependent Claim
21 words
A circuit for a heating system as claimed in claim 2 wherein the control switch means is a semi-conductive switch device.
Claim 5
Dependent Claim
207 words
A circuit for a heating system comprising a plurality of thermally operated relays, each having normally open first and second switches and a heat motor, said first and second switches being closable by energizing the respective heat motor for at least a predetermined duration, a blower motor serially connected with the first normally open switch of a first of the plurality of relays, a plurality of electric heating elements, each of said plurality of electric heating elements being connected in series with the first normally open switch of respective relays of the plurality of relays. the heat motor of each relay except the first relay of the plurality of relays being connected in series with the second switches of respective preceding relays, control switch means for energizing the heat motor of the first relay, said control switch means having a control electrode which when energized operates the control switch means, thermostat means for energizing the control electrode of the control switch means at temperatures below a selected temperature, and for deenergizing the heat motor of a second relay at temperature above the selected temperature, means sensing energization of any of the plurality of electric heating elements and connected to the control electrode for energizing the control electrode.
Claim 6
Dependent Claim
207 words
A circuit for a heating system comprising a plurality of thermally operated relays, each having normally open first and second switches and a heat motor, said first and second switches being closable by energizing the respective heat motor for at least a predetermined duration, a blower motor serially connected with the first normally open switch of a first of the plurality of relays, a plurality of electric heating elements, each of said plurality of electric heating elements being connected in series with the first normally open switch of respective relays of the plurality of relays. the heat motor of each relay except the first relay of the plurality of relays being connected in series with the second switches of respective preceding relays, control switch means for energizing the heat motor of the first relay, said control switch means having a control electrode which when energized operates the control switch means, thermostat means for energizing the control electrode of the control switch means at temperatures below a selected temperature, and for deenergizing the heat motor of a second relay at temperature above the selected temperature, means sensing energization of any of the plurality of electric heating elements and connected to the control electrode for energizing the control electrode.
Claim 7
Dependent Claim
70 words
A circuit for a heating system as claimed in claim 4 wherein there are included a plurality of lines, each connected in series with a respective one of the heating elements, and the control electrode energizing means include a ferro-magnetic core inductively coupled to all of the plurality of lines, and a pick up coil wound on the magnetic core for energizing the control electrode of the control switch means.
Claim 8
Dependent Claim
20 words
A circuit for a heating system as claimed in claim 5 wherein the control switch means is a semi-conductive element.
Claim 9
Dependent Claim
32 words
A circuit for a heating system as defiNed in claim 4 wherein the heat motor of each relay includes a snap-acting bimetal element, and electric heating means for heating the bimetal element.
Claim 10
Dependent Claim
102 words
A circuit for a heating system as defined in claim 7 wherein the snap-acting bimetal element is an elongated strip-like bimetal element formed with a transverse curvature which is straightened by transverse temperature warp of the bimetal element produced by increasing temperature, said transverse curvature retaining the bimetal element against longitudinal curvature until a temperature is reached whereat longitudinal curvature forces exceed retaining forces of the transverse curvature producing a snap longitudinal curvature change, and the electric heating means includes a thermoconductive support for supporting one end of the bimetal element and an electrical resistance heating winding wound on the thermoconductive support.
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) | 1978-10-13 | 1979-04-14 | 1979-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-13 | 1983-04-14 | 1983-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-13 | 1987-04-14 | 1987-10-14 | $7700.00 | Window Closed / Lapsed |