Fuel filter unit with water content indicator
First Claim
1. Fuel filter unit equipped for detection of water in the filter unit, comprising a water sensor (1) for providing a signal when water in said filter unit reaches a predetermined quantity or level, an evaluation circuit including an indicator (8, 36) for producing a warning in response to appearance of said signal and circuit means connected to said evaluation circuit for reduction of the current in said sensor after appearance of said signal without substantially affecting the output of said evaluation circuit which is provided to said indicator (8, 36), said circuit means including a first transistor (22) having its controlled path connected in parallel to said sensor (1) and its control electrode connected in circuit for causing said transistor to become conductive during the provision of said output of said indicator.
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Accused Products
Abstract
Corrosion of a water sensor resulting from the passage of considerable electric current through it while it is in contact with water is prevented in a motor fuel filter equipped for water separation by interrupting or greatly reducing the current passing through the sensor after the sensor has given a signal indicating the presence of water in sufficient quantity to require draining soon. The warning provided to the vehicle driver is maintained thereafter either by a signal storage circuit (flipflop) or by causing current diverted from the sensor to flow through a substitution resistor or a shunt transistor.
22 Citations
6 Claims
- 1. Fuel filter unit equipped for detection of water in the filter unit, comprising a water sensor (1) for providing a signal when water in said filter unit reaches a predetermined quantity or level, an evaluation circuit including an indicator (8, 36) for producing a warning in response to appearance of said signal and circuit means connected to said evaluation circuit for reduction of the current in said sensor after appearance of said signal without substantially affecting the output of said evaluation circuit which is provided to said indicator (8, 36), said circuit means including a first transistor (22) having its controlled path connected in parallel to said sensor (1) and its control electrode connected in circuit for causing said transistor to become conductive during the provision of said output of said indicator.
Specification