US3876037A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid level sensing device
Assignee: Nycal Co Inc
•
Filing: 1973-07-30
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Granted: 1975-04-08
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Expires: 1993-07-30
Abstract
Abstract A liquid level sensing device intended to sense the level of oil in an engine crank case with means for filling the case with oil from a reserve tank if the oil level is below a desired level. The sensing device is a thermistor having a negative coefficient of resistance. It is wired to a bridge circuit containing a Zener diode for a voltage reference. The circuit is operated by a manual push button and an SCR made conductive. If the oil level is below the desired level, a solenoid valve opens a conduit to a reserve tank and the crank case is automatically filled.
Inventors
- 👤 Jr Harry B Rath
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:10
CPC Classifications
F; F01; F01M; F01M11/00; F01M11/10; F01M11/12; F01M11/06; F01M11/061; G; G01; G01F; G01F23/00; G01F23/22; G01F23/24; G01F23/246; G01F23/247; Y; Y10; Y10T; Y10T137/00; Y10T137/7287; Y10T137/7306
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
198 words
A device for sensing and replenishing the liquid level in a main tank wherein said main tank is connected to a machine to be lubricated comprising a first liquid containing main tank, a reserve liquid containing tank, a fluid bearing line interconnecting the main and reserve tanks, an oil pump connected between the main tank and the machine for circulating the oil therethrough, an oil pressure switch coupled to the oil pump, liquid level sensing means comprising a four armed bridge circuit, a thermistor in one of said arms, said thermistor disposed within the main tank at a desired level, a source of potential connected to the thermistor to raise the temperature of the said thermistor to a desired point, a normally closed solenoid valve in the fluid bearing line, a winding in the solenoid valve coupled to the bridge circuit, switch means for energizing the bridge circuit whereby the solenoid valve is opened to admit liquid from the reserve tank to the main tank in the event the liquid level is below the desired level, said switch means being operated by the oil pressure switch to open the switch whenever the oil pressure exceeds a predetermined value.
Claim 2
Independent Claim
198 words
A device for sensing and replenishing the liquid level in a main tank wherein said main tank is connected to a machine to be lubricated comprising a first liquid containing main tank, a reserve liquid containing tank, a fluid bearing line interconnecting the main and reserve tanks, an oil pump connected between the main tank and the machine for circulating the oil therethrough, an oil pressure switch coupled to the oil pump, liquid level sensing means comprising a four armed bridge circuit, a thermistor in one of said arms, said thermistor disposed within the main tank at a desired level, a source of potential connected to the thermistor to raise the temperature of the said thermistor to a desired point, a normally closed solenoid valve in the fluid bearing line, a winding in the solenoid valve coupled to the bridge circuit, switch means for energizing the bridge circuit whereby the solenoid valve is opened to admit liquid from the reserve tank to the main tank in the event the liquid level is below the desired level, said switch means being operated by the oil pressure switch to open the switch whenever the oil pressure exceeds a predetermined value.
References Cited (Backward Citations)
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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) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |