US4140023A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential pressure transducer
Assignee: Bourns Inc
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Filing: 1978-02-09
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Granted: 1979-02-20
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Expires: 1998-02-09
Abstract
Abstract A piezoresistive differential pressure transducer in which the need for convoluted isolating diaphragms and oil fill is eliminated. The instrument as contemplated by the invention does not require O-ring seals or springs to provide over-pressure protection. The absence of convoluted diaphragms and oil minimizes inherent errors due to temperature variations and static line pressure effect.
Inventors
- 👤 Ronald Edwards
- 👤 Terence K. Rhind
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:30
CPC Classifications
G; G01; G01L; G01L9/00; G01L9/0041; G01L9/0051; G01L9/0052; G01L9/0055
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
82 words
A dry piezoresistive differential pressure transducer comprising: a machined metal center section; a relatively thin circular center section formed in said machined metal center section; piezoresistive elements fused to the relatively thin circular section; a protective layer covering the piezoresistive elements; a flat isolating disc covering said protective layer; end fittings fastened to said machined metal center section; means for applying pressures to said pressure transducer through said end fittings; and means for connecting said piezoresistive elements exteriorly of said pressure transducer.
Claim 2
Dependent Claim
82 words
A dry piezoresistive differential pressure transducer comprising: a machined metal center section; a relatively thin circular center section formed in said machined metal center section; piezoresistive elements fused to the relatively thin circular section; a protective layer covering the piezoresistive elements; a flat isolating disc covering said protective layer; end fittings fastened to said machined metal center section; means for applying pressures to said pressure transducer through said end fittings; and means for connecting said piezoresistive elements exteriorly of said pressure transducer.
Claim 3
Dependent Claim
14 words
The pressure transducer of claim 1, wherein said protective layer is formed of epoxy.
Claim 4
Dependent Claim
17 words
The pressure transducer of claim 1, wherein said piezoresistive elements are connected in a Wheatstone bridge arrangement.
Claim 5
Dependent Claim
19 words
The pressure transducer of claim 3, wherein said piezoresistive elements are connected in alternate positive and negative gage configuration.
Claim 6
Dependent Claim
27 words
The pressure transducer of claim 1, wherein said relatively thin circular center section has a low center step forming a mechanical support for the flat isolating disc.
Claim 7
Independent Claim
64 words
A method of making a laminated pressure sensitive sensor comprising the steps of: machining a relatively thin circular center section; forming a cup-like center in said circular center section; fusing piezoresistive elements to the inside bottom of said cup-like center; covering the piezoresistive elements with a protective layer; connecting the piezoresistive elements exteriorly of the transducer; overlaying the protective layer with an isolating disc.
Claim 8
Independent Claim
64 words
A method of making a laminated pressure sensitive sensor comprising the steps of: machining a relatively thin circular center section; forming a cup-like center in said circular center section; fusing piezoresistive elements to the inside bottom of said cup-like center; covering the piezoresistive elements with a protective layer; connecting the piezoresistive elements exteriorly of the transducer; overlaying the protective layer with an isolating disc.
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) | 1982-02-19 | 1982-08-21 | 1983-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-19 | 1986-08-21 | 1987-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-19 | 1990-08-21 | 1991-02-20 | $7700.00 | Window Closed / Lapsed |