US3884079A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Force balance differential pressure transmitter
Assignee: SPX Technologies Inc
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Filing: 1973-11-05
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Granted: 1975-05-20
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Expires: 1993-11-05
Abstract
Abstract A differential pressure transmitter, including a gauge, which embodies a novel form of force-balance system that eliminates the need for levers, pivots and critical flexures. The system is designed for a wide range of differential pressure and utilizes a relatively strong magnet as part of the feedback motor such that the feedback coil of the motor can act directly upon the pressure sensing bellows at the input, the bellows being responsive to difference in pressure thereat.
Inventors
- 👤 Quentin C Turtle
- 👤 Pasco A Coia
- 👤 John R Silva
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:28
CPC Classifications
G; G01; G01L; G01L11/00; G01L11/004; G01L11/008; G01L13/00; G01L13/02; G01L13/023
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
132 words
A force-balance differential pressure transmitter, comprising: a casing having first and second pressure chambers therein; a pressure sensing device for measuring the difference in pressure between the two chambers, said device having an initial position; a linear variable differential transformer including a core movable in response to movement of said pressure sensing device; feedback means, including a feedback coil for receiving current derived from said transformer, said coil being operable to restore said pressure sensing device substantially to its initial position; a common direct current power supply and a two-wire transmission line or loop connected to said power supply, including means for both transmitting signal current over the transmission line to a central station and for deriving bi-polar voltages serving as local power supplies at the location for said differential pressure transmitter.
Claim 2
Dependent Claim
132 words
A force-balance differential pressure transmitter, comprising: a casing having first and second pressure chambers therein; a pressure sensing device for measuring the difference in pressure between the two chambers, said device having an initial position; a linear variable differential transformer including a core movable in response to movement of said pressure sensing device; feedback means, including a feedback coil for receiving current derived from said transformer, said coil being operable to restore said pressure sensing device substantially to its initial position; a common direct current power supply and a two-wire transmission line or loop connected to said power supply, including means for both transmitting signal current over the transmission line to a central station and for deriving bi-polar voltages serving as local power supplies at the location for said differential pressure transmitter.
Claim 3
Dependent Claim
25 words
Apparatus as defined in claim 1, further comprising: amplifying means in said feedback means, and means for supplying said bi-polar voltages to said amplifying means.
Claim 4
Dependent Claim
34 words
Apparatus as defined in claim 2, further comprising a power output stage and a feedback path in said power output stage, and potentiometer means for adjusting to the output current range to be handled.
Claim 5
Dependent Claim
113 words
A force-balance differential pressure transmitter, comprising: a casing having first and second pressure chambers therein; a pressure sensing device for measuring the difference in pressure between the two chambers, said device having an initial position; a linear variable differential transformer including a core movable in response to movement of said pressure sensing device; feedback means, including amplifying means and a feedback coil for receiving current derived from said transformer, said coil being operable to restore said pressure sensing device substantially to its initial position; integrating means as part of said feedback means, said integrating means comprising a capacitor and resistor in series and connected between the input and output of said amplifying means.
Claim 6
Dependent Claim
113 words
A force-balance differential pressure transmitter, comprising: a casing having first and second pressure chambers therein; a pressure sensing device for measuring the difference in pressure between the two chambers, said device having an initial position; a linear variable differential transformer including a core movable in response to movement of said pressure sensing device; feedback means, including amplifying means and a feedback coil for receiving current derived from said transformer, said coil being operable to restore said pressure sensing device substantially to its initial position; integrating means as part of said feedback means, said integrating means comprising a capacitor and resistor in series and connected between the input and output of said amplifying means.
Claim 7
Dependent Claim
16 words
Apparatus as defined in claim 4, further including a diode connected in shunt with said capacitor.
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) | 1978-05-19 | 1978-11-18 | 1979-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-19 | 1982-11-18 | 1983-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-19 | 1986-11-18 | 1987-05-20 | $7700.00 | Window Closed / Lapsed |