40 (i.e. in one single piece).

The top plate 42 defines a central opening forming an outlet path for the filtered liquid. This central opening opens to the central volume of the media 38. In other words, the top plate central opening is in direct communication with the internal volume of the filter media 38, i.e. the filtered liquid inside the media 38 can escape directly upwards through the top plate opening.

Also, the central tube 33 is radially set back from the inner wall of the filter media 38.

In the example, the central tube 33 is fixed, in particular clipped, to one of the two plates 40 and 42, in particular to the bottom plate 40.

Advantageously, the central tube 33 passes through the top plate 42, i.e. the central tube 33 is received inside the opening of the top plate 42, so that the filtered liquid passes between the tube 33 and the top plate opening, and tube 10 protrudes upwards compared to the rest of filter element 32.

During operation, and as shown in FIG. 3, the fuel to be filtered enters the filter housing 30 through radial hole(s) extending through the center tube 33. The fuel then flows through the entire length of tube 33 (Arrow A1). The fuel then passes through the bottom plate 40 through the sealed connection between tube 10 and plate 8, flows up by the sides of the media 38 and accumulates in the volume around the filter media 4 (Arrow A2). The fuel then passes through the filter media 38 in a substantially radial direction to the central axis X38 of the media 38 (Arrow A3). The fuel, then filtered, flows up along the central tube 33, passes through passage sections between tube 33 and the top plate opening and joins an outlet channel (not shown) extending through the filter head 36 (See arrow A4).

In the example, the center tube 33 has fins that drive the fuel flow in a helical direction (See arrow A4 on FIG. 3) around the centre axis X38. This has the advantage of guiding the flow of filtered fuel to the top and creating a dynamic flow behaviour. In other words, this enables avoiding that the fuel flows downwardly and accumulates in the lower portion of the filter.

Typically, and as shown on FIG. 4, the liquid to be filtered enters inside the filter housing 30 through a central passage and that the fileted liquid flows out of the filter housing 30 through a central passage as well. Typically, the outlet passage is coaxially arranged around the inlet passage.

As shown on FIGS. 4 and 5, the filter head 36 is specific in that it includes an anti-leakage valve 50 (also known as “inlet valve”) comprising a closing element 52 that is movable between a closed position (represented on FIG. 5) in which it closes off the inlet port 19 and an open position (represented on FIG. 4) in which the liquid can flow through the inlet port 19.

In the example, and as it is usual for this type of valve, the closing element 52 of valve 50 cooperates with a valve seat. This valve seat is part of the filter head 36.

Advantageously, the valve seat is made of rubber, which avoids using an additional seal ring.

Besides, the filter 12 further includes a pin 54 that is fitted on the filter element 32 and that is configured to penetrate inside the inlet port 19 so as to move the closing element 52 from the closed position to the open position.

Precisely, the closing element 52 is movable axially, i.e. along a direction that is parallel to axis X38. The closing element 52 is by default closing the inlet port 19 under the effect of gravity. When the pin 54 penetrates into the inlet port 19, it pushes the closing element 52 up, which uncovers a passage for liquid through the inlet port 19. When the filter housing 30 is dismounted, the pin 54 moves out of the inlet port 19 and the closing element 52 moves back into the closed position under the effect of gravity. Accordingly, valve 50 stops the inlet flow of fuel through the inlet port 19, meaning that no fuel drops onto the floor or onto the operator while the filter element 32 is replaced.

In the example, the closing element 52 is a plunger (or piston).

Typically, the pin 54 is arranged at the centre of the top end plate 42. In the example, the pin 54 extends axially upwards. It protrudes upwards relative to the rest of the filter element 32.

In the example of the figures, and although this is not properly shown, filter head 36 includes another outlet channel (not shown) communicating with the return line 18. A degassing valve is preferably included in said other channel. As its names indicates, the degassing valve opens to let the gas (typically air) inside the filter housing to flow back to the fuel tank and is closed off as soon as the filter housing is filled up with liquid. As such degassing valve is well known from prior art, it is not described in further details.

In the embodiment of the figures, the filter head 36 delimits an inlet channel 37 arranged upstream of the inlet port 19.

Thanks to this anti-leakage valve 50, the inlet port is automatically closed when there is no filter element 32, because the closing element 52 is by default closing the inlet port 19. Accordingly, if there is no filter element 32, then no fuel will flow through the inlet port 19 and the liquid filter 12 will not be supplied with fuel. The engine will be able to start. However, it will automatically stop after a short time period due to lack of fuel supply. The same defect could be observed if the filter element that is in the system (i.e. that is in the filter housing 30) is not designed for this specific application (i.e. if the filter element is not provided with a pin 54). This is called “No filter No run”.

In one non-represented alternative embodiment, the filter head 36 delimits another outlet port (not shown) and a bypass (not shown) extending between the inlet channel 37 and said other outlet port. In that case, the closing element 52 is arranged so that it closes off the bypass in the open position (FIG. 4) and so that the bypass is open as long as the closing element is in closed position (FIG. 5).

FIGS. 6 to 8 represent the pre-filter 6, which can be seen as another embodiment of the invention. Only the differences relative to the main filter 12 are depicted here-below, for concision purpose.

A first difference between the pre-filter 6 and the main filter 12 is that the pin 54 fitted on the filter element 32 is arranged eccentrically with respect to the central axis X38 of the filter medium 38.

Another difference is that the closing element