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US 3,940,980 AGranted
Oil well pressure sensing system
AssigneeWhittaker Corporation
InventorsHomer G. Tasker, William F. Green
Life of this patent
Estimating the term…
Abstract
An oil well fluid depth or pressure sensing system for sensing pressures adjacent the bottom of the oil well and providing signals on the surface indicative of the pressure range in the well. The sensor comprises a pressure sensitive switch utilizing a nestable welded bellows. Information is transmitted to the surface through a single wire, with grounded shield return. A phase sensitive detector circuit is located at the surface for providing signals indicative of normal pressures, over pressures and under pressures, as well as any malfunction in the system.
Claims13
A pressure sensor comprising;
- a case means defining a first enclosure,
- a differential pressure responsive means forming a part of the wall of said case,
- means for responding to the differential pressure across said differential pressure responsive means,
- first and second switch means coupled to said differential pressure responsive means and operative to provide first and second switching signals at first and second differential pressures,
- first and second diodes each coupled in series with said first and second switch means respectively, said first diode and said first switch means being coupled in parallel with said second diode and said second switch means to form a network forming first and second circuit means respectively, said network being coupled to first and second electrical connections, said network having predeterminedly different electrical characteristics when measured between said first and second electrical connections with the respective switch means closed;
- and
- means for coupling said first electrical connection to a cable conductor.
4 more elements
A pressure sensor comprising;
- a first enclosure,
- a nestable bellows means defining a part of the wall of said first enclosure and responsive to the difference in pressure external to and internal to said first enclosure, said nested bellows means nesting to resist said difference in pressure above a predetermined value within said first enclosure,
- first and second switch means within said first enclosure and coupled to said bellows and operative to provide first and second switching signals at first and second differential pressures respectively,
- first and second diodes each coupled in series with said first and second switch means respectively, said first diode and said first switch means being coupled in parallel with said second diode and said second switch means to form a network forming first and second circuit means respectively, said network being coupled to first and second electrical connections, said network having predeterminedly different electrical characteristics when measured between said first and second electrical connections with the respective switch means closed;
- and,
- means for coupling said first electrical connection to a cable conductor.
3 more elements
A system for sensing pressures comprising:
- a cable comprised of a single insulated conductor and a conductor shield,
- a pressure sensor having a means responsive to fluid pressure surrounding said pressure sensor, and first and second switch means responsive to motion of said means responsive to fluid pressure to provide first and second switching signals, said first and second switch means each being coupled in series with first and second diodes respectively, between said conductor and said conductor shield, said first and second diodes forming first and second circuit means respectively having a predeterminedly different electrical characteristic when measured between said conductor and said conductor shield with the respective said switch means closed, and
- an electronic circuit having a third circuit means coupled in series with said conductor and a means for applying an AC signal between said third circuit means and said cable shield, said electronic circuit having means coupled to said conductor for detecting the state of said first and second switch means by detecting voltages characteristic of the series combination of said first and third circuit means, and said third circuit means in series with the parallel combination of said first and second circuit means.
Dependencies are inferred from the claim text.