DRIVING CIRCUIT OF FUEL LEVEL GAGE

Japanese Patent JPH05273026

A

PURPOSE:To enable stable indication of the quantity of fuel even when a fuel tank has a structure in which the liquid level of the fuel fluctuates in a large degree, by providing a time constant switching circuit which receives an output voltage of a fuel sensor and changes a time constant of a damper circuit in accordance with the current quantity of the fuel. CONSTITUTION:A time constant switching circuit constructed of a switch 14 receiving an output voltage of a fuel sensor 1 of which the output voltage changes in accordance with the quantity of fuel in a fuel tank 2 and changing a time constant of a damper circuit 8 in accordance with the current quantity of the fuel, and of a comparator 15, is provided. In the case when the quantity of the fuel 4 is larger than 1/2 of the quantity of the fuel 4 at the time when the fuel is filled up in the fuel tank 2, the time constant tau is made small, while the time constant tau is made large when the quantity of the fuel 4 is smaller than the 1/2 as the boundary. Even when the output voltage of the fuel sensor 1 varies due to the large fluctuation of the liquid level of the fuel 4 occurring when the quantity of the fuel 4 inside the fuel tank 2 is small, the variation is absorbed by the damper circuit of the large time constant corresponding to the quantity of the fuel, oscillation of a fuelometer is eliminated and stable indication of the quantity of the fuel is enabled, according to this constitution.

Koji Sugimoto

JP7414592A

October 22, 1993

March 30, 1992

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Yazaki Corporation

G01F23/30; G01F25/00; G01F23/00; (IPC1-7): G01F23/00; G01F23/30; G01F25/00

JPS58206928A

1983-12-02

Yasushi Kobayashi (1 person outside)

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