US3620520A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Furnace heating control system
Assignee: SECO/WARWICK Corp (A PA CORP)
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Filing: 1970-07-29
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Granted: 1971-11-16
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Expires: 1990-07-29
Abstract
Abstract A furnace heating control system for a furnace using a gaseous heating media that passes through the workload for rapidly bringing the workload up to the desired processing temperature without any ''''overshoot'''' of the workload temperature. This control is accomplished solely as a function of the incoming and outgoing temperatures of the gaseous heating media through the workload. In combination with a reversible axial flow fan synchronously switched thermocouples continuously measure the incoming and outgoing temperatures, electrical signals proportional to the incoming and outgoing temperatures are compared to respective reference signals and any resulting excess signals are used to effect reversal of a motor normally driving a heat input valve in a direction so as to increase the heat input. In one embodiment a heating media temperature signal is compared against a variable reference signal which is proportional to the difference between the incoming and outgoing temperatures of the gaseous heating media.
Inventors
- 👤 Robert H Ross
- 👤 Robert C Larko
- 👤 Walter G Swartzfager
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:58
CPC Classifications
C; C21; C21D; C21D11/00; G; G05; G05D; G05D23/00; G05D23/19; G05D23/1927; G05D23/193; G05D23/1932; G05D23/1934; G05D23/20; G05D23/22
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
230 words
In a heat treat furnace having a furnace enclosure for containing a workload to be processed, a circulating heating media which passes through the workload, means for heating said media, and reversible means normally operating to increase the heat input to said media, a control system for maintaining the temperature of the heating media at the valve in excess of a preselected temperature for processing the workload for a time determinable as a function of the temperatures of the heating media as it passes through the workload, comprising first means for generating a first temperature signal directly proportional to the temperature of the heating media prior to said media passing through the workload, second means for generating a second temperature signal directly proportional to a temperature of the heating media, third means for generating a preselected signal and fourth means for generating a reference signal, first circuit means for comparing said first temperature signal with said preselected signal and for generating a first operating signal when said first temperature signal exceeds said preselected signal to reverse said reversible means to decrease the heat input to said media, and second circuit means for comparing said second temperature signal with said reference signal and for generating a second operating signal when said second temperature signal exceeds said reference signal to reverse said reversible means to decrease the heat input to said media.
Claim 2
Dependent Claim
230 words
In a heat treat furnace having a furnace enclosure for containing a workload to be processed, a circulating heating media which passes through the workload, means for heating said media, and reversible means normally operating to increase the heat input to said media, a control system for maintaining the temperature of the heating media at the valve in excess of a preselected temperature for processing the workload for a time determinable as a function of the temperatures of the heating media as it passes through the workload, comprising first means for generating a first temperature signal directly proportional to the temperature of the heating media prior to said media passing through the workload, second means for generating a second temperature signal directly proportional to a temperature of the heating media, third means for generating a preselected signal and fourth means for generating a reference signal, first circuit means for comparing said first temperature signal with said preselected signal and for generating a first operating signal when said first temperature signal exceeds said preselected signal to reverse said reversible means to decrease the heat input to said media, and second circuit means for comparing said second temperature signal with said reference signal and for generating a second operating signal when said second temperature signal exceeds said reference signal to reverse said reversible means to decrease the heat input to said media.
Claim 3
Dependent Claim
69 words
The control system of claim 1 wherein said preselected signal is directly proportional to a maximum temperature setting for the heating media prior to said media passing through the workload, and said reference signal is directly proportional to the preselected temperature for processing the workload plus a preselected ratio of a signal directly proportional to the temperature difference of the media resulting from the media passing through the workload.
Claim 4
Dependent Claim
29 words
The control system of claim 2 wherein said second temperature signal is directly proportional to the temperature of the heating media after said media has passed through the workload.
Claim 5
Dependent Claim
29 words
The control system of claim 2 wherein said second temperature signal is directly proportional to the temperature of the heating media prior to said media passing through the workload.
Claim 6
Dependent Claim
80 words
The control system of claim 1 wherein said preselected signal is directly proportional to a maximum temperature setting for the heating media prior to said media passing through the workload, said second temperature signal is directly proportional to the temperature of the heating media after said media has passed through the workload and said reference signal is a second preselected signal directly proportional to a maximum temperature setting for said heating media after said media has passed through the workload.
Claim 7
Dependent Claim
38 words
The control system of claim 5 wherein said maximum temperature for the heating media after said media has passed through the workload is equal to the upper limit of a tolerance range for the preselected workload processing temperature.
Claim 8
Dependent Claim
80 words
The control system of claim 2 having a timer to indicate the length of time that the workload has been maintained at the preselected processing temperature, fifth means for generating a second preselected signal directly proportional to a temperature setting and third circuit means for comparing the signal directly proportional to said temperature difference with said second preselected signal and for generating a third operating signal when said temperature difference signal exceeds said second preselected signal to activate said timer.
Claim 9
Dependent Claim
333 words
In a heat treat furnace having a furnace enclosure for containing a workload to be processed, means for circulating a heating media through the workload, first reversible means for reversing the diRection of circulation of the heating media, means for heating said media, and second reversible means normally operating to increase the heat input to said media, a control system for maintaining the temperature of the heating media at a value in excess of a preselected temperature for processing the workload for a time determinable as a function of the temperatures of the heating media as it passes through the workload, comprising at least first and second thermocouples positioned respectively at opposite ends of the path of circulation of the heating media through the workload, first means including at least one thermocouple for generating a first temperature signal directly proportional to the temperature of the heating media prior to said media passing through the workload, second means, including at least one thermocouple, for generating a second temperature signal directly proportional to a temperature of the heating media, third means for generating a preselected signal and fourth means for generating a reference signal, first circuit means for comparing said first temperature signal with said preselected signal and for generating a first operating signal when said first temperature signal exceeds said preselected signal to reverse said second reversible means to decrease the heat input to said media, second circuit means for comparing said second temperature signal with said reference signal and for generating a second operating signal when said second temperature signal exceeds said reference signal to reverse said second reversible means to decrease the heat input to said media and third reversible means synchronously operable with said first reversing means such that said first thermocouple and said second thermocouple can be automatically selectively interconnected with said first means for generating said first temperature signal and said second means for generating said second temperature signal depending upon the direction of circulation of the heating media.
Claim 10
Dependent Claim
333 words
In a heat treat furnace having a furnace enclosure for containing a workload to be processed, means for circulating a heating media through the workload, first reversible means for reversing the diRection of circulation of the heating media, means for heating said media, and second reversible means normally operating to increase the heat input to said media, a control system for maintaining the temperature of the heating media at a value in excess of a preselected temperature for processing the workload for a time determinable as a function of the temperatures of the heating media as it passes through the workload, comprising at least first and second thermocouples positioned respectively at opposite ends of the path of circulation of the heating media through the workload, first means including at least one thermocouple for generating a first temperature signal directly proportional to the temperature of the heating media prior to said media passing through the workload, second means, including at least one thermocouple, for generating a second temperature signal directly proportional to a temperature of the heating media, third means for generating a preselected signal and fourth means for generating a reference signal, first circuit means for comparing said first temperature signal with said preselected signal and for generating a first operating signal when said first temperature signal exceeds said preselected signal to reverse said second reversible means to decrease the heat input to said media, second circuit means for comparing said second temperature signal with said reference signal and for generating a second operating signal when said second temperature signal exceeds said reference signal to reverse said second reversible means to decrease the heat input to said media and third reversible means synchronously operable with said first reversing means such that said first thermocouple and said second thermocouple can be automatically selectively interconnected with said first means for generating said first temperature signal and said second means for generating said second temperature signal depending upon the direction of circulation of the heating media.
Claim 11
Dependent Claim
69 words
The control system of claim 8 wherein said preselected signal is directly proportional to a maximum temperature setting for the heating media prior to said media passing through the workload, and said reference signal is directly proportional to the preselected temperature for processing the workload plus a preselected ratio of a signal directly proportional to the temperature difference of the media resulting from the media passing through the workload.
Claim 12
Dependent Claim
80 words
The control system of claim 8 wherein said preselected signal is directly proportional to a maximum temperature setting for the heating media prior to said media passing through the workload, said second temperature signal is directly proportional to the temperature of the heating media after said media has passed through the workload and said reference signal is a second preselected signal directly proportional to a maximum temperature setting for said heating media after said media has passed through the workload.
References Cited (Backward Citations)
US1923145A
Cited
US3447790A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |