Abstract A temperature-regulating system to maintain the temperature of liquid containers in a hybrid process tank at a desired level, the vessel being constituted by an inner plastic vessel and an outer metallic jacket provided with heater elements. The jacket functions as a heat distributor to uniformly distribute the thermal energy applied to the interface of the vessel and the jacket, which energy is transferred by the plastic vessel to the liquid at a relatively slow rate. In order to raise the temperature of the liquid to the desired level and to maintain the liquid at this level without overheating and damaging the vessel, the system includes a first temperature-sensing resistor disposed at the interface of a heated plate and the plastic vessel, and a second temperature-sensing resistor immersed in the liquid, whereby the resistance of the first sensor reflects the quickly rising interface temperature and the resistance of the second sensor reflects the slowly rising liquid temperature. The two sensors are connected in series in one arm of a bridge that controls the application of power to the heater elements, the power being turned off when the bridge output determined by the ratio of the resistances of the sensors, attains a null.
An electronic controller for regulating the temperature of a solution contained in a plastic tank heated by electrical heaters mounted on plates secured to the wall of the tank, said controller comprising: A. a plate sensor in thermal contact with and responsive to the temperature of one of the plates and constituted by a resistor whose resistance increases with temperature; B. a solution sensor immersed in and responsive to the temperature of the solution and constituted by a resistor whose resistance increases with temperature; C. a bridge circuit having an input voltage applied thereto and including said sensors and arranged to yield a null output when the sensors have a predetermined resistance ratio and to yield an offset voltage output when the sensors depart from said ratio; and D. means responsive to said offset voltage to apply electrical energy derived from a source thereof to said heaters as a function of the varying value of said offset voltage whereby when the solution is relatively cold, the resistance of the plate sensor is high relative to said solution sensor and said heaters are energized intermittently to prevent overheating of the plate.
Claim 2
Dependent Claim
190 words
An electronic controller for regulating the temperature of a solution contained in a plastic tank heated by electrical heaters mounted on plates secured to the wall of the tank, said controller comprising: A. a plate sensor in thermal contact with and responsive to the temperature of one of the plates and constituted by a resistor whose resistance increases with temperature; B. a solution sensor immersed in and responsive to the temperature of the solution and constituted by a resistor whose resistance increases with temperature; C. a bridge circuit having an input voltage applied thereto and including said sensors and arranged to yield a null output when the sensors have a predetermined resistance ratio and to yield an offset voltage output when the sensors depart from said ratio; and D. means responsive to said offset voltage to apply electrical energy derived from a source thereof to said heaters as a function of the varying value of said offset voltage whereby when the solution is relatively cold, the resistance of the plate sensor is high relative to said solution sensor and said heaters are energized intermittently to prevent overheating of the plate.
Claim 3
Dependent Claim
30 words
A controller as set forth in claim 1, wherein said sensors are connected in series in one leg of the bridge, another leg of which includes a variable set-point potentiometer.
Claim 4
Dependent Claim
19 words
A controller as set forth in claim 2, wherein the other two legs of the bridge include fixed resistors.
Claim 5
Dependent Claim
31 words
A controller as set forth in claim 1, wherein a constant voltage is applied to the input diagonals of the bridge and said output is derived from the output diagonals thereof.
Claim 6
Dependent Claim
37 words
A controller as set forth in claim 1, wherein said sensor resistors are placed in one pair of opposing legs of the bridge and two set point potentiometers are placed in the remaining pair of opposing legs.
Claim 7
Dependent Claim
27 words
A controller as set forth in claim 1, wherein said solution sensor is enclosed in the bottom leg of a looped-shaped metal tube immersed in said solution.
Claim 8
Dependent Claim
18 words
A controller as set forth in claim 6, wherein said metal tube is sheathed in a plastic tube.