US3823726A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pneumatic control unit
Assignee: Honeywell Inc
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Filing: 1972-06-30
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Granted: 1974-07-16
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Expires: 1992-06-30
Abstract
Abstract A precision pneumatic proportional derivative or proportional integral derivative controller having a plurality of pistons each one of which forms a different portion of a balancing beam. Each piston is arranged to pass through a different one of several spaced apart cylindrical passageways formed by inner wall portions of the casing of said controller. A separate rolling diaphragm is connected in fluid tight sealing engagement with each piston and with its associated wall portion to form a rolling seal therebetween. The diameters of these pistons are of predetermined sizes in relation to their associated passageway diameters. As a result, a predetermined difference or offset is allowed to exist between positive and negative feedback forces applied to the balancing beam, thereby allowing the output offset of the controller to deviate from a zero value while it is maintaining its loop gain at a proper value.
Inventors
- 👤 T Umeda
- 👤 T Shiga
- 👤 M Ando
- 👤 N Wada
- 👤 T Akiyama
- 👤 R Fikuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 00:58
CPC Classifications
F; F15; F15C; F15C4/00; Y; Y10; Y10T; Y10T137/00; Y10T137/2278; Y10T137/2365; Y10T137/2409; Y10T137/2452
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
466 words
A pneumatic control unit, comprising a cylindrical housing having first and second passageways at opposite end portions thereof and a third passageway intermediate said first and second passageways, all of said passageways being of the same size and in alignment with the axis of said cylindrical housing, a piston associated with each of said passageways, a balancing beam extending through said passageways in alignment with the axis of said housing and arranged for axial movement with said pistons in their associated passageways, the diameter of the piston in one end of said housing being smaller than the diameter of the other pistons, a separate rolling diaphragm associated with each of said pistons that are at the opposite ends of said housing for sealing the associated passageways, a separate rolling diaphragm associated with each of the opposite ends of said third piston for sealing the opposite ends of said intermediate passageway, a first bellows providing a seal with said balancing beam at its closed end and a position intermediate a first end one of said pistons and the intermediate piston and providing a seal at its open end with an associated internal wall of said housing, a second bellows providing a seal with said balancing beam at its closed end at a position intermediate the other end one of said pistons and said intermediate Piston and providing a seal at its open end with an associated internal wall of said housing, each of said bellows forming the common wall of adjacent chambers, a conduit connection through the wall of said housing to each of said chambers, means to apply through said conduit connections to the opposite sides of the common wall formed by said first bellows setpoint and process variable fluid pressures, means to apply through one of tqhe remaining conduit connections that is associated with the chamber having said smallest piston a positive feedback fluid pressure, means to apply to the other one of said remaining conduits a negative feedback fluid pressure, said negative feedback and positive feedback fluid pressures being applied to the opposite sides of the common wall formed by said second bellows, said last mentioned bellows being associated with said piston of smaller diameter, a nozzle flapper device associated with said balancing beam for converting displacement of said beam into an output fluid pressure having a magnitude corresponding to the magnitude of such displacement, and means to apply said output fluid pressure to the opposite sides of said second bellows, the diameter of the piston in the positive feedback chamber end of the housing with which said second mentioned bellows is associated being of said smaller diameter than said other pistons whereby improvement is obtained in the output offset of said controller without affecting the value of the loop gain of said controller.
Claim 2
Dependent Claim
466 words
A pneumatic control unit, comprising a cylindrical housing having first and second passageways at opposite end portions thereof and a third passageway intermediate said first and second passageways, all of said passageways being of the same size and in alignment with the axis of said cylindrical housing, a piston associated with each of said passageways, a balancing beam extending through said passageways in alignment with the axis of said housing and arranged for axial movement with said pistons in their associated passageways, the diameter of the piston in one end of said housing being smaller than the diameter of the other pistons, a separate rolling diaphragm associated with each of said pistons that are at the opposite ends of said housing for sealing the associated passageways, a separate rolling diaphragm associated with each of the opposite ends of said third piston for sealing the opposite ends of said intermediate passageway, a first bellows providing a seal with said balancing beam at its closed end and a position intermediate a first end one of said pistons and the intermediate piston and providing a seal at its open end with an associated internal wall of said housing, a second bellows providing a seal with said balancing beam at its closed end at a position intermediate the other end one of said pistons and said intermediate Piston and providing a seal at its open end with an associated internal wall of said housing, each of said bellows forming the common wall of adjacent chambers, a conduit connection through the wall of said housing to each of said chambers, means to apply through said conduit connections to the opposite sides of the common wall formed by said first bellows setpoint and process variable fluid pressures, means to apply through one of tqhe remaining conduit connections that is associated with the chamber having said smallest piston a positive feedback fluid pressure, means to apply to the other one of said remaining conduits a negative feedback fluid pressure, said negative feedback and positive feedback fluid pressures being applied to the opposite sides of the common wall formed by said second bellows, said last mentioned bellows being associated with said piston of smaller diameter, a nozzle flapper device associated with said balancing beam for converting displacement of said beam into an output fluid pressure having a magnitude corresponding to the magnitude of such displacement, and means to apply said output fluid pressure to the opposite sides of said second bellows, the diameter of the piston in the positive feedback chamber end of the housing with which said second mentioned bellows is associated being of said smaller diameter than said other pistons whereby improvement is obtained in the output offset of said controller without affecting the value of the loop gain of said controller.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-15 | 1978-01-14 | 1978-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-15 | 1982-01-14 | 1982-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-15 | 1986-01-14 | 1986-07-16 | $7700.00 | Window Closed / Lapsed |