US3849770A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for detecting decrease of liquid in a liquid reservoir
Assignee: Tokico Ltd
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Filing: 1973-04-24
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Granted: 1974-11-19
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Expires: 1993-04-24
Abstract
Abstract A device for detecting decrease of liquid comprising a permanent magnet having vertically disposed poles which moves downwardly with decrease of the liquid in a liquid reservoir, a reed switch disposed horizontally in the reservoir and closed by lines of magnetic force of the permanent magnet when the permanent magnet moves down to a position of predetermined height and an alarm means actuated by closing of the reed switch.
Inventors
- 👤 Y Hayashida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:02
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/30; G01F23/64; G01F23/72; G01F23/74; G01F23/14; G01F23/18; G01F23/185
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
244 words
A device for detecting decrease of liquid comprising: a liquid reservoir storing liquid therein, said liquid reservoir having a lower bottom surface and including a shoulder portion projecting from said lower bottom surface, said shoulder portion being provided in the vicinity of the upper surface thereof with a blind hole extending substantially horizontally in the shoulder portion; a conduit disposed in proximity to the lower bottom surface of the liquid reservoir, said conduit being at a level lower than the blind hole and communicating with the interior of the liquid reservoir; float means movable upwardly and downwardly with change of quantity of the liquid in the reservoir; a permanent magnet centrally secured in said float means and having magnetic poles disposed vertically, said permanent magnet being of a columnar configuration; a normally open reed switch disposed in said blind hole in the shoulder portion of the liquid reservoir, said reed switch including reeds with contact portions disposed at a position transversely offset from the axis of the permanent magnet by a distance at least equal to the radius of the permanent magnet; said reed switch being closed by a horizontal component of magnetic flux from the permanent magnet when tHe liquid decreases below a predetermined level and said permanent magnet with said float means has reached a position of a predetermined spacing from the reed switch; and means coupled to said reed switch for producing an output signal upon closing of the reed switch.
Claim 2
Independent Claim
244 words
A device for detecting decrease of liquid comprising: a liquid reservoir storing liquid therein, said liquid reservoir having a lower bottom surface and including a shoulder portion projecting from said lower bottom surface, said shoulder portion being provided in the vicinity of the upper surface thereof with a blind hole extending substantially horizontally in the shoulder portion; a conduit disposed in proximity to the lower bottom surface of the liquid reservoir, said conduit being at a level lower than the blind hole and communicating with the interior of the liquid reservoir; float means movable upwardly and downwardly with change of quantity of the liquid in the reservoir; a permanent magnet centrally secured in said float means and having magnetic poles disposed vertically, said permanent magnet being of a columnar configuration; a normally open reed switch disposed in said blind hole in the shoulder portion of the liquid reservoir, said reed switch including reeds with contact portions disposed at a position transversely offset from the axis of the permanent magnet by a distance at least equal to the radius of the permanent magnet; said reed switch being closed by a horizontal component of magnetic flux from the permanent magnet when tHe liquid decreases below a predetermined level and said permanent magnet with said float means has reached a position of a predetermined spacing from the reed switch; and means coupled to said reed switch for producing an output signal upon closing of the reed switch.
Claim 3
Dependent Claim
66 words
A device for detecting decrease of liquid as claimed in claim 1 in which said liquid reservoir is substantially of a cylindrical configuration, said float means comprising a float floating on the liquid, said float being in the form of a disc having an outer diameter which is slightly smaller than the inner diameter of said reservoir, said permanent magnet being centrally buried in said disc.
Claim 4
Dependent Claim
88 words
A device for detecting decrease of liquid as claimed in claim 1 in which said float means comprises a bellows which encloses the liquid between the outer surface thereof and the inner surface of the liquid reservoir and stretches as the liquid decreases, and a guide plate fixedly attached to the bellows at the lower bottom surface thereof and having an outer diameter slightly smaller than the inner diameter of the liquid reservoir, said permanent magnet being secured at the center of the bottom surface of said bellows.
Claim 5
Dependent Claim
64 words
A device for detecting decrease of liquid as claimed in claim 1 further comprising a bellows dividing the space above the liquid surface in said reservoir into two parts, said bellows including at the bottom thereof a one-way valve which permits air to flow only from a first space in said bellows to a second space defined between said bellows and the liquid surface.
Claim 6
Dependent Claim
128 words
A device for detecting decrease of liquid as claimed in claim 1 in which said means for producing an output signal comprises an alarm means actuated by being connected to a power source through the closed reed switch, said liquid reservoir being made of a conductive material and electrically connected to the negative pole of the power source, and a socket made of a conductive and non-magnetic material holding the reed switch therein, said socket being electrically connected to one reed of the reed switch and to the liquid reservoir by contact with the inner surface of the blind hole in an inserted state in the blind hole, the other reed of said reed switch being electrically connected to said alarm means by means of a single wire.
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) | 1977-11-18 | 1978-05-20 | 1978-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-18 | 1982-05-20 | 1982-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-18 | 1986-05-20 | 1986-11-19 | $7700.00 | Window Closed / Lapsed |