US5247833A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Water level measuring apparatus
Assignee: Fujitsu Ltd
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Filing: 1992-08-04
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Granted: 1993-09-28
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Expires: 2012-08-04
Abstract
Abstract An apparatus for measuring a water level of a dam by combining a pressure type water level gauge measuring the water level by detecting water pressure at a bottom of the dam, with a plurality of float type water level switches arranged along the depth of the dam and provided at an interval less than a tolerance allowed to the gauge. Obtaining a water level difference between the water level measured by the gauge and the water level at the switch respectively, the gauge water level is corrected to a water level obtained by subtracting the difference at one of the switches from the gauge water level, when a water surface of the dam is located between the one of the switches and the gauge or an adjacent switch. The abnormality of the gauge is found by detecting whether the difference exceeds a water level tolerance allowed to the gauge.
Inventors
- 👤 Toshihisa Sasaya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 21:55
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/14; G01F23/30; G01F23/64; G01F23/72; G01F23/74; G01F25/00; G01F25/20; G01F25/22; H; H01; H01H; H01H36/00; H01H36/02
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
297 words
An apparatus for measuring a water level of a dam, said apparatus comprising: a pressure type water level gauge (1) comprising a water pressure detector (11) set on a bottom (201) of the dam for detecting pressure of the water in the dam, said gauge converting the detected water pressure to a water level of the dam and producing a datum on the water level; a plurality of float type water level switches (3a, 3b and 3c) arranged on support means in the dam and spaced at intervals along a depth of the dam to detect water surface movements at different levels of the dam, each interval between the bottom and one of said switches placed just above the bottom and between other ones of said switches and an adjacent switch being less than a measuring span tolerance in water level measurement of said gauge, and each of said switches producing an ON-OFF signal every time a water surface of the dam passes through said switch; means (44) for obtaining in response to an ON-OFF signal produced by a switch, a datum on a correction value being a water level difference between the water level at that switch and the water level measured by said gauge, each time the water surface passes through that switch; and correction means (46) for correcting, due to the ON-OFF signal, the water level measured by said gauge to a water level obtained by subtracting the datum on the correction value at said switch through which the water surface has passed most recently, from the datum on the water level measured by said gauge, when the water surface is located between the water pressure detector and said one switch placed just above the bottom or between adjacent ones of said switches, respectively.
Claim 2
Independent Claim
297 words
An apparatus for measuring a water level of a dam, said apparatus comprising: a pressure type water level gauge (1) comprising a water pressure detector (11) set on a bottom (201) of the dam for detecting pressure of the water in the dam, said gauge converting the detected water pressure to a water level of the dam and producing a datum on the water level; a plurality of float type water level switches (3a, 3b and 3c) arranged on support means in the dam and spaced at intervals along a depth of the dam to detect water surface movements at different levels of the dam, each interval between the bottom and one of said switches placed just above the bottom and between other ones of said switches and an adjacent switch being less than a measuring span tolerance in water level measurement of said gauge, and each of said switches producing an ON-OFF signal every time a water surface of the dam passes through said switch; means (44) for obtaining in response to an ON-OFF signal produced by a switch, a datum on a correction value being a water level difference between the water level at that switch and the water level measured by said gauge, each time the water surface passes through that switch; and correction means (46) for correcting, due to the ON-OFF signal, the water level measured by said gauge to a water level obtained by subtracting the datum on the correction value at said switch through which the water surface has passed most recently, from the datum on the water level measured by said gauge, when the water surface is located between the water pressure detector and said one switch placed just above the bottom or between adjacent ones of said switches, respectively.
Claim 3
Dependent Claim
49 words
An apparatus according to claim 1 further comprising means (5) for detecting abnormality of said gauge in operation, by detecting whether the datum on the correction value exceeds an allowed datum on a water level allowed to said gauge having as far as said gauge is normal in operation.
Claim 4
Dependent Claim
46 words
An apparatus according to claim 2 further comprising memory means (43) for storing data on water levels at said switches and the allowed datum, said ON-OFF signal triggering said memory means to read out the stored data from said memory means for performing said correction means.
Claim 5
Dependent Claim
49 words
An apparatus according to claim 3 further comprising means (47) for producing an initial ON-OFF signal for triggering said memory means to read out the datum on the water level at said switch located closest to the water surface when said gauge and switches are initially operated after installation.
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) | 1996-09-27 | 1997-03-29 | 1997-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-27 | 2001-03-29 | 2001-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-09-27 | 2005-03-29 | 2005-09-28 | $7700.00 | Window Closed / Lapsed |