Patent ID: 9072992
Filing Date: 2015-07-07
Classification: B01D

Abstract:
1. A fuel filter of a combustion engine capable of diagnosing operative and non-operative states, the fuel filter comprising: a filter housing; a replaceable filter insert that is insertable into the filter housing; a switch element that is movable between a contact position and an interrupt position; two electrical conductors that are connectible to the switch element; a water collection chamber that collects water separated from fuel; and a water level sensor that is connected to the electrical conductors when the filter insert is inserted into the housing, such that the electrical conductors extend down into the water collection chamber; wherein a resistance value and a capacitance value of the electrical conductors to each other varies as a function of the presence or absence of the filter insert in the filter housing; wherein the two electrical conductors are electrically connectible with each other via the water when the water level is high enough to reach the electrical conductors, and are also electrically connectible to the switch element; wherein the resistance value that exists between the two electrical conductors has a first value when the switch element is in the contact position and a second value that differs from the first value when the switch element is in the interrupt position.