Liquid level sensor for e.g. petrol tank - has pivoted float connected to slider arm of volatile liq. resistance resistance variable resistor

摘要

The liquid level sensing system comprises a variable resistor (1) having a substrate (9) comprising insulating material resistant to volatile liquids (e.g. petrol or petrol/alcohol mixtures) and on it there is printed a resistive layer (8), which provides the requisite law characteristic according to the shape of the container of the volatile liquid. The wiper contact (3) is arranged to selectively connect part of the printed resistive layer in circuit to vary the effective resistance value of the resistor in response to the actuation of a float or equivalent device as the liquid level changes in the container. The float is coupled to an extension (7) so that wiper assembly (2) pivots about a pin (5). The substrate may be ceramic or porcelainised steel and the resistive layer a composition of glass frit and a precious metal or metal oxide.