US3901437A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Programmed temperature control system for a furnace and the like
Assignee: Electronic Control Systems Inc
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Filing: 1974-02-04
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Granted: 1975-08-26
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Expires: 1994-02-04
Abstract
Abstract A furnace or kiln for firing ceramic ware includes a thermocouple which supplies an output signal that is proportional to the temperature within the furnace. A slidewire potentiometer provides an output signal that corresponds to a preselected maximum temperature to be reached in the furnace to a first summing amplifier. The first summing amplifier compares the output received from the thermocouple with the output from the slidewire potentiometer as heat is supplied to the furnace. A variable voltage generator, such as a ramp generator, is operatively associated with the first summing amplifier to control the rates of heating and cooling in the furnace. The output of the ramp generator is controlled by a Zener diode network to independently adjust the intervals and rates of heating and cooling within the furnace. A combination amplifier and relay device responds to the input received from the ramp generator and the thermocouple to control the power supplied to the furnace. Power is supplied to the furnace when the output from the thermocouple exceeds that of the ramp generator. A second summing amplifier receives input from the first amplifier and actuates the ramp generator to increase or decrease the input to the power control amplifier to thereby raise or lower the furnace temperature. In this manner, a control is established to maintain the output of the ramp generator at a level equal to the output of the slidewire potentiometer. When the temperature within the furnace has risen to the preselected level as indicated by the output from the thermocouple, the second summing amplifier actuates the ramp generator to provide an output to the power control amplifier at a reduced voltage level to reduce the furnace temperature at a controlled rate which may be equal to or vary from the rate of temperature increase.
Inventors
- 👤 Robert E Harkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:52
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/22; G05D23/1902
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
171 words
A programmed temperature control system for a furnace comprising, means for sensing the temperature within said furnace, means for indicating the temperature within said furnace, means for setting a fixed preselected maximum temperature within said furnace, variable voltage means for increasing and decreasing the temperature of said furnace at a controlled rate, means for controlling the supply of power to said furnace responsive to output of said variable voltage means, first amplifier means for receiving input signals from said temperature sensing means and said tempeRature setting means, second amplifier means for receiving input signals from said first amplifier means, said temperature setting means and said variable voltage means to maintain said variable voltage means at the output of said temperature setting means for an indefinite period of time until the temperature in said furnace reaches said preselected maximum temperature, and diode means for controlling the input of signals from said second amplifier means to said variable voltage means to thereby adjust the rate of temperature increase and decrease in said furnace.
Claim 2
Dependent Claim
171 words
A programmed temperature control system for a furnace comprising, means for sensing the temperature within said furnace, means for indicating the temperature within said furnace, means for setting a fixed preselected maximum temperature within said furnace, variable voltage means for increasing and decreasing the temperature of said furnace at a controlled rate, means for controlling the supply of power to said furnace responsive to output of said variable voltage means, first amplifier means for receiving input signals from said temperature sensing means and said tempeRature setting means, second amplifier means for receiving input signals from said first amplifier means, said temperature setting means and said variable voltage means to maintain said variable voltage means at the output of said temperature setting means for an indefinite period of time until the temperature in said furnace reaches said preselected maximum temperature, and diode means for controlling the input of signals from said second amplifier means to said variable voltage means to thereby adjust the rate of temperature increase and decrease in said furnace.
Claim 3
Dependent Claim
86 words
A programmed temperature control system for a furnace as set forth in claim 1 in which said variable voltage means includes, a ramp generator arranged to receive input signals from said diode means and provide a corresponding output signal to said means for controlling the supply of power to said furnace at a preselected rate, and said diode means operable to actuate said ramp generator to increase the furnace temperature to said preselected maximum temperature and thereafter decrease the furnace temperature therefrom to room ambient temperature.
Claim 4
Dependent Claim
82 words
A programmed temperature control system for a furnace as set forth in claim 1 which includes, said first amplifier means for receiving input signals includes a first summing amplifier, said second amplifier means for receiving input signals includes a second summing amplifier, a blocking diode connecting said first and second summing amplifiers, said blocking diode operable to prevent signal input supplied from said first summing amplifier to said second summing amplifier until the temperature in said furnace reaches said preselected maximum temperature.
Claim 5
Dependent Claim
50 words
A programmed temperature control system for a furnace as set forth in claim 1 which includes, feedback means for adjusting the output of said variable voltage means to a magnitude of the output of said maximum temperature setting means to thereby control the rate of temperature increase in said furnace.
Claim 6
Dependent Claim
153 words
A programmed temperature control system for a furnace as set forth in claim 3 which includes, said first summing amplifier operable to provide an output signal when the temperature within said furnace reaches said preselected maximum temperature, and said second summing amplifier arranged to supply output signals of both forward and reverse polarity to said variable voltage means for first increasing the output signal of said variable voltage means until the magnitude thereof exceeds the output signal of said temperature setting means, said second summing amplifier thereafter operable to alternately increase and decrease the output signal of said variable voltage means and thereby maintain the output signal thereof equal to the output signal of said temperature setting means for a indefinite period of time until said second summing amplifier receives an input signal from said first summing amplifier and supplies an output signal for decreasing the output signal of said variable voltage means.
Claim 7
Dependent Claim
61 words
A programmed temperature control system for a furnace as set forth in claim 5 which includes, means for delaying the input signal to said second summing amplifier from said first summing amplifier for a predetermined period of time so that the temperature within the furnace remains at said preselected maximum temperature for a predetermined period of time before beginning to decrease.
Claim 8
Dependent Claim
112 words
A programmed temperature control system for a furnace as set forth in claim 6 in which said delaying means includes, a solid state switching device, and a solid state delay timer arranged to provide said solid state switching device with an output signal for a predetermined period of time from the time said first summing amplifier reverses in polarity corresponding to the time at which the temperature in said furnace exceeds said preselected maximum temperature, said solid state switching device operable to withhold the output signal of said first summing amplifier from the input of said second summing amplifier when said solid state switching device receives input from said solid state timer.
Claim 9
Dependent Claim
183 words
A programmed temperature control system for a furnace as set forth in claim 4 in which said feedback means includes, said second amplifier means, said variable voltage means, a Zener diode network arranged to receive input signals from said second amplifier means and to supply input signals to said variable voltage means, said Zener diode network having a plurality of Zener diodes of preselected breakdown voltages such that the input signals to said variable voltage means are controlled by a selected one of said Zener diodes, and means for regulating the power supplied to said furnace to thereby raise and lower the temperature of said furnace, said variable voltage means operable to actuate said power regulating means and raise the temperature of said furnace in response to the input signals from said second amplifier means, said second amplifier means operable to monitor the output signals of said temperature setting means and responsively supply input signals to said variable voltage means so that said regulating means supplies power to said furnace to heat said furnace to the temperature provided by said temperature setting 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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |