US3739337A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fuel gauge operating circuits for road vehicles
Assignee: ZF International UK Ltd
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Filing: 1971-03-09
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Granted: 1973-06-12
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Expires: 1991-03-09
Abstract
Abstract A fuel gauge operating circuit for a road vehicle has a pair of supply lines powered by the vehicle battery and a thermally operable voltage regulator including a vibrating contact through which the fuel gauge is connected to one supply line. The fuel gauge is connected to the other supply line through a variable resistor the value of which is determined by the level of the fuel in the fuel tank, and a transistor is connected in series with the warning lamp between the supply lines. A switching circuit is connected between the supply lines in series with the voltage regulator contact, and the switching circuit has an input connection to the junction of the fuel gauge and the variable resistor and an output connection to the base of the transistor so that the warning lamp flashes when the fuel level is low.
Inventors
- 👤 W Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:03
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/24; G01F23/246; G01F23/247
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
197 words
A fuel gauge operating circuit for a road vehicle, including a pair of supply lines for connection to the vehicle battery, a fuel gauge including a thermally sensitive element the current flow through which determines the reading of the gauge, a thermally operable voltage regulator including a contact through which the fuel gauge is connected to one supply line, the contact opening and closing to regulate the voltage applied to the fuel gauge, a variable resistor through which the fuel gauge is connected to the other supply line, the value of said variable resistor being determined by the level of fuel in the fuel tank, a transistor connected in series with a warning lamp between the supply lines, and a switching circuit connected between the supply lines in series with the voltage regulator contact, the switching circuit having an input connection to the junction of the fuel gauge and the variable resistor, and an output connection to the base of the transistor, and serving when the level of fuel in the fuel tank falls to a predetermined value to turn on the transistor, so that the warning lamp flashes under the control of the voltage regulator contact.
Claim 2
Dependent Claim
197 words
A fuel gauge operating circuit for a road vehicle, including a pair of supply lines for connection to the vehicle battery, a fuel gauge including a thermally sensitive element the current flow through which determines the reading of the gauge, a thermally operable voltage regulator including a contact through which the fuel gauge is connected to one supply line, the contact opening and closing to regulate the voltage applied to the fuel gauge, a variable resistor through which the fuel gauge is connected to the other supply line, the value of said variable resistor being determined by the level of fuel in the fuel tank, a transistor connected in series with a warning lamp between the supply lines, and a switching circuit connected between the supply lines in series with the voltage regulator contact, the switching circuit having an input connection to the junction of the fuel gauge and the variable resistor, and an output connection to the base of the transistor, and serving when the level of fuel in the fuel tank falls to a predetermined value to turn on the transistor, so that the warning lamp flashes under the control of the voltage regulator contact.
Claim 3
Dependent Claim
33 words
A circuit as claimed in claim 1 in which the switching circuit and the transistor constitute a bridge network so that the operating circuit is not sensitive to the voltage of the battery.
Claim 4
Dependent Claim
30 words
A circuit as claimed in claim 1 including a further switch which is operated in response to a predetermined condition, the warning lamp being illuminated when the switch is closed.
Claim 5
Dependent Claim
22 words
A circuit as claimed in claim 3 in which the further switch is closed when the handbrake of the vehicle is applied.
Claim 6
Dependent Claim
17 words
A circuit as claimed in claim 3 in which the further switch is connected across the transistor.
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) | 1976-06-11 | 1976-12-11 | 1977-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-11 | 1980-12-11 | 1981-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-11 | 1984-12-11 | 1985-06-12 | $7700.00 | Window Closed / Lapsed |