US3593577A
Expired / Lapsed
US
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Adiabatic calorimeter control system
Assignee: Parr Instrument Co
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Filing: 1968-04-22
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Granted: 1971-07-20
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Expires: 1988-04-22
Abstract
Abstract A control system utilized for an adiabatic calorimeter including a pair of thermistors positioned in the bucket and the jacket of a calorimeter and connected to an off-null electrical bridge circuit that actuates one of two relays controlling the flow of hot and/or cold water to the calorimeter jacket. A signal from the bridge indicating an imbalance in the thermistor temperatures is amplified in two stages and fed to a thyristor. Depending on the phase of the signal, one relay will be actuated while the other relay is blocked; one relay controlling the addition of small amounts of hot or cold water and the other relay controlling the addition of a large amount of hot water when the sample in the calorimeter is ignited.
Inventors
- 👤 Ray J Monner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:15
CPC Classifications
G; G01; G01K; G01K17/00; G05; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1912; G05D23/1927; G05D23/193; G05D23/1931; G05D23/20; G05D23/24
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
214 words
A control system for use in regulating a first condition relative to a second condition comprising a pair of sensing elements capable of sensing each condition and converting it into an electrical value, a bridge circuit for the sensing elements, means for placing the bridge circuit in an off-null condition, an amplifier receiving a signal from the bridge circuit, a thyristor receiving the amplified signal and being controlled by said signal, and a phase sensitive circuit including a pair of loops connected to said thyristor, each loop containing a relay and a diode, a center-tapped secondary transformer winding connecting said loops with the center tap leading to the thyristor, said thyristor providing a signal upon triggering that is in phase with one of the two loops to actuate the relay therein, the diode in the unactuated loop blocking actuation of the relay in the unactuated loop, said off-null condition of the bridge circuit producing a signal to trigger the thyristor and cause the loop in phase therewith to actuate the relay in the loop whereby corrective action may be initiated to drive the first condition to a point causing the thyristor to extinguish, deactivating the relay and whereby reverse corrective action may then be initiated to return the first condition to its former state.
Claim 2
Dependent Claim
214 words
A control system for use in regulating a first condition relative to a second condition comprising a pair of sensing elements capable of sensing each condition and converting it into an electrical value, a bridge circuit for the sensing elements, means for placing the bridge circuit in an off-null condition, an amplifier receiving a signal from the bridge circuit, a thyristor receiving the amplified signal and being controlled by said signal, and a phase sensitive circuit including a pair of loops connected to said thyristor, each loop containing a relay and a diode, a center-tapped secondary transformer winding connecting said loops with the center tap leading to the thyristor, said thyristor providing a signal upon triggering that is in phase with one of the two loops to actuate the relay therein, the diode in the unactuated loop blocking actuation of the relay in the unactuated loop, said off-null condition of the bridge circuit producing a signal to trigger the thyristor and cause the loop in phase therewith to actuate the relay in the loop whereby corrective action may be initiated to drive the first condition to a point causing the thyristor to extinguish, deactivating the relay and whereby reverse corrective action may then be initiated to return the first condition to its former state.
Claim 3
Dependent Claim
88 words
A control system as set forth in claim 1, in which a relatively large change in the second condition being sensed by one of the sensing elements will cause the bridge circuit to pass through its balanced condition to the opposite side to a second off-null condition where a signal is generated in the opposite phase to trigger the thyristor and cause actuation of the opposite loop to actuate the relay whereby the first condition can be driven towards a balanced state by instituting a second corrective action.
Claim 4
Dependent Claim
77 words
A control system as set forth in claim 1, in which said thyristor acts as a switch to allow current flow in only one direction, a diode positioned across the gate of the thyristor to prevent triggering from a voltage reversal, and an additional diode in each loop positioned on the opposite side of the lead to the relay from the first-mentioned loop diode to prevent oscillations from the relay from causing false operation of the thyristor.
Claim 5
Dependent Claim
93 words
A control system as set forth in claim 1, in which said sensed condition is temperature and the temperatures of the sensing elements are slightly unequal with the bridge in its off-null condition, each loop of said phase-sensitive circuit operating independently, and solenoid valves controlling hot and cold water, the relay in one loop operating said solenoid valves for introducing alternate flows of hot and cold water to one of said sensing elements, thus causing continuous excursions above and below the point at which the temperature of the two sensing elements are equal.
Claim 6
Dependent Claim
99 words
A control system as set forth in claim 1, in which said sensing elements are thermistors which translate temperature change into resistance change, said bridge circuit comprising a wheatstone bridge having said thermistors in a pair of legs, a pair of resistors in the other two legs, an alternating current bias supply for the bridge, said means to place the bridge circuit in an off-null condition being a potentiometer located at the intersection of the legs containing said resistors, a lead from the potentiometer extending to said amplifier, and means to provide a constant voltage for said bridge circuit.
Claim 7
Dependent Claim
36 words
A control system as set forth in claim 5, in which said amplifier is a two-step amplification system employing a pair of transistors, and a diode bridge providing a direct current power supply for said amplifier.
Claim 8
Dependent Claim
95 words
A control system as set forth in claim 1, including a low-flow cold water solenoid valve, a low-flow hot water solenoid valve and a high-flow hot water solenoid valve, said relay in one loop actuating a switch arm between a normally closed contact actuating the low-flow hot water solenoid valve and a normally open contact which, when closed, actuates the low-flow cold water solenoid valve, and said relay in the opposite loop has a switch arm which, when the last-mentioned relay is actuated, closes a normally open contact actuating the high-flow hot water solenoid valve.
Claim 9
Dependent Claim
57 words
A control system as set forth in claim 7, in which said solenoid valves control hot and cold water flow to an adiabatic calorimeter having a bucket and a jacket, and said sensing elements comprise a pair of thermistors, one of which is positioned in the calorimeter jacket and the other is positioned in the calorimeter bucket.
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) | 1974-07-19 | 1975-01-18 | 1975-07-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-19 | 1979-01-18 | 1979-07-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-19 | 1983-01-18 | 1983-07-20 | $7700.00 | Window Closed / Lapsed |