Patent ID: 7392783

Claim:
A fuel filter system in the form of a fuel filter in a fuel line ( 9 ′) leading to the internal combustion engine, having a replaceable filter element ( 4 ) in a divisible filter housing, comprising a valve ( 14 ) provided inside the fuel line ( 9 ′) prevents the internal combustion engine from being started with unfiltered fuel; the valve ( 14 ) is opened due to the position of the filter element ( 4 ) when a filter element ( 4 ) is present inside the filter housing, and when there is no filter element ( 4 ), the valve is closed due to the fuel pressure applied to the filter housing fuel inlet opening ( 9 ) under active filter operating pressure; the divisible filter housing consists of a pot-shaped housing bottom part ( 1 ) having an opening opposite its bottom and a cover in the form of a housing top part ( 2 ) which can close this opening when in an operation-ready state; a stand pipe ( 3 ), which is hollow on the inside, protrudes from the bottom to the aforementioned opening of the housing bottom part ( 1 ); the stand pipe ( 3 ) directs fuel that has been filtered in the filter element ( 4 ) to the outside of the filter housing; the stand pipe has a radial opening ( 11 ) in the clean room ( 8 ) of the filter; a pipe slide ( 12 ) is displaceably mounted on the stand pipe ( 3 ) as part of a pipe slide valve ( 14 ); the pipe slide ( 12 ) has a radial opening ( 13 ) which is aligned with the radial opening ( 11 ) of the stand pipe in a corresponding displacement position of the pipe slide ( 12 ) with respect to the stand pipe ( 3 ); the pipe slide ( 12 ) assumes different positions with respect to the stand pipe ( 3 ), depending on whether or not there is a filter element ( 4 ) in the filter housing, namely a first position when a filter element ( 4 ) is inserted and a second position when there is no filter element; and in the first position it is possible for fuel to flow from the stand pipe ( 3 ) and the pipe slide ( 12 ) through the radial openings ( 11 , 13 ) that are aligned and flush with one another, whereas this is impossible in the second position.