Liquid filter equipped with a leak-proof valve

Abstract

The invention relates to a liquid filter (6, 12), preferably a fuel filter, for a vehicle, the filter comprising a filter head (36) delimiting an inlet port (19) and an outlet port (21), a filter housing (30) screwed below the filter head (36) and housing a filter element (32) centered on a central axis (X38), said filter element comprising a filter medium (38), a top end plate (42) and a bottom end plate (40). The filter housing (30) delimits a first space for housing a flow of liquid to be filtered, said first space being delimited radially around the filter medium (38) and communicating with the inlet port (19), and a second space for housing a flow of filtered liquid, said second space being delimited radially inside the filter medium (38) and communicating with the outlet port (21). The filter head (36) comprises an anti-leakage valve (50) comprising a closing element (52) movable between a closed position in which it closes the inlet port (19) and an open position in which liquid can flow through the inlet port (19), and a pin (54) fitted on the filter element (32) and configured to penetrate into the inlet port (19) in order to move the closing element (52) from the closed position to the open position.

Description

TECHNICAL FIELD

[0001] The present invention relates to a liquid filter, typically a fuel filter, equipped with a leak-proof valve. The invention is mainly applied to fuel filtration, but it is also conceivable to use the same principle in oil circuits.

[0002] The invention can be applied to heavy vehicles, such as trucks, buses and construction equipment. Although the invention will be described with respect to a truck, the invention is not limited to this particular vehicle, but can also be used in other vehicles, such as passenger cars, and more generally in any vehicle comprising an internal combustion engine. BACKGROUND

[0003] Liquid filters are usually provided in vehicles to remove contaminants from the liquid, which can be fuel or oil, for example.

[0004] A conventional filter element of a liquid filter comprises a tubular filter medium, arranged at its end portions with two end plates mounted in a sealing manner on the axial end portions of the medium. Typically, the top plate comprises a central opening in fluid communication with the interior space of the medium. The filter element is housed within a filter housing, typically made of aluminum, which is to be attached under a filter head, also called a "casting", comprising an inlet port and an outlet port.

[0005] Thus, the liquid to be filtered flows through the inlet of the filter head, through the filter medium, and then the filtered liquid can exit the filter element through the central opening of the top plate and finally flow through the outlet of the filter head.

[0006] Since the filter medium becomes gradually clogged, the filter element needs to be replaced regularly so that it remains efficient. To this end, the filter housing is detached from the casting, the old filter element is removed, a new filter element is inserted in the filter housing and the filter housing is mounted back on the casting.

[0007] Today, when the housing is removed from the filter head, it is necessary to close the fuel inlet to avoid fuel dripping on the operator during the maintenance work. Furthermore, it is also necessary to prevent the engine from running without a filter element or with an unsuitable filter element, which is also commonly referred to as the "no filter, no run" function.

[0008] In this regard, EP 2 029 885 B1 discloses a fuel filter in which the filter element comprises a pin arranged to close the return line to the fuel tank when the filter element is correctly inserted into the filter housing. Thus, in the absence of the closing element and / or in the absence of the filter element, the return line is open so that the fuel supplied through the inlet into the filter housing preferably flows out through the return line and, for example, back into the fuel tank. In this case, no fuel or not enough fuel is supplied. Subsequently, the internal combustion engine cannot be started.

[0009] However, this document does not disclose any solution to prevent fuel from splashing onto the floor when the filter housing is removed from the said casting during maintenance work.

[0010] US 5 698 093 discloses a fuel filter equipped with a valve system for closing the fuel inlet when the housing containing the filter element is separated from the said casting. The valve system comprises a plurality of valve stems which, when the filter element is correctly introduced, are pushed upwards by the filter element, which involves opening the inlet passage for the unfiltered fuel inside the housing, while, when the filter element is removed, the valve stems move downwards due to gravity, which involves closing the said inlet passage.

[0011] This publication discloses a solution to prevent the engine from running in the absence of the filter element. However, it does not solve the case in which the filter element introduced inside the said housing is an unsuitable filter element.

[0012] US 5,591,332 discloses a fluid filter assembly in which the housing comprises a cylindrical neck (134) protruding upwards from the center of the cap (124) and in which, when the filter housing is assembled to the said casting, the neck (134) pushes the piston (18) upwards and exposes the inlet opening (76). A cylindrical protrusion (139) extends downwards from the bottom of the cap (124) around the central return hole (138). When the filter housing (60) is removed from the casting (10), the piston return spring (22) pushes the piston (18) downwards, causing the piston filter to face the radial opening (76) to stop the fluid flow.

[0013] The fluid filter assembly disclosed in this publication does not have the "no filter, no run" function because: it can work even in the absence of filter medium arranged inside the filter housing.

[0014] US 6,171,491 B1 discloses a filter wherein the free end (224) of the actuating tab (222) is positioned to engage the valve element (196) and move it away from the opening (198) so that fluid can flow from the central fuel chamber (212) through the opening (198) when the filter element (98) is engaged to the head. This enables the central fuel chamber of the element to be connected with the outlet (102) of the head. SUMMARY

[0015] It is an object of the present invention to provide a mechanism to close the fuel inlet when the filter housing is unscrewed from the filter head and to avoid fuel drops on the operator. It is another object to use the same mechanism to implement a "no filter, no run" function, i.e. to be able to detect when there is no filter element in the filter housing or when the filter element in the filter housing is not a proper filter element.

[0016] To this end, the present invention relates to a liquid filter, preferably a fuel filter, for a vehicle, the filter comprising:

[0017] - a filter head delimiting an inlet port and an outlet port;

[0018] - a filter housing screwed under the filter head and housing a filter element centered on a central axis, the filter element comprising a filter medium, a top end plate and a bottom end plate,

[0019] wherein the filter housing delimits a first space for housing a flow of liquid to be filtered, the first space being delimited radially around the filter medium and in communication with the inlet port, and a second space for housing a flow of filtered liquid, the second space being delimited radially inside the filter medium and in communication with the outlet port.

[0020] According to the invention, the filter head comprises a leak-proof valve comprising a closing element movable between a closed position in which it closes the inlet port and an open position in which liquid can flow through the inlet port, and the filter further comprises a pin fitted on the filter element and configured to penetrate into the inlet port so as to move the closing element from the closed position to the open position.

[0021] The term "fitted on the filter element" is to be understood as meaning that the pin can be attached to the filter element or integral with the filter element, in particular with the top plate.

[0022] With the present invention, the inlet port is automatically closed when there is no filter element, since the closing element will close the inlet port by default. Thus, if there is no filter element, no fuel will flow through the inlet port and the liquid filter device will not be supplied with fuel. The engine will be able to start. However, due to the lack of fuel supply, the engine will automatically stop after a short period of time. The same defect can be observed if the filter element in the system is not designed for this particular application (i.e. if the filter element is not provided with a pin). This is referred to as "no filter, no run".

[0023] According to other advantageous but non-mandatory aspects of the present invention, the liquid filter of the present invention can be considered to comprise one or more of the following features, alone or in combination:

[0024] - the filter head further comprises indexing means for guiding the pin towards the inlet port when screwing the filter housing to the filter head until the pin reaches a configuration wherein the pin is axially aligned with the first port.

[0025] Thus, when the filter head is screwed on the filter housing to reach the mounted configuration, the indexing means cooperate with the pin to obtain the configuration wherein the pin is axially aligned with the first port. This means that the pin is first turned around the central axis and then reaches the configuration wherein the pin stops rotating and the pin penetrates axially into the inlet port when the filter housing remains screwed on the filter head. When the filter housing is unscrewed, the closing element moves to the closed position before the filter housing is completely unscrewed. This makes it possible to avoid liquid dripping when replacing the filter element. Moreover, thanks to this arrangement, it is not necessary to take into account the orientation of the pin with respect to the filter head. The indexing or alignment of the pin and the inlet port is automatic when screwing the filter housing from below. The indexing means maintain the pin in the configuration (aligned configuration) when screwing the filter housing from below.

[0026] - the filter element is rotationally fixed with the filter housing and the pin is part of a ring rotatably mounted on the top end plate of the filter element.

[0027] - the filter element is rotationally movable with respect to the filter housing and the pin is part of the top end plate of the filter element.

[0028] - the pin is arranged eccentrically with respect to the central axis.

[0029] - the pin is arranged at the center of the top end plate.

[0030] - the pin extends axially upwards.

[0031] - the closure element is a ball or a plunger.

[0032] This makes it possible for the liquid to circulate easily in the open position of the closure element. Since the ball or plunger has a simple geometry and can be moved easily, interruption of the liquid communication is achieved in a reliable manner without the pin.

[0033] - the filter head delimits an inlet channel arranged upstream of the inlet port, a further outlet port and a bypass extending between the inlet channel and the further outlet port.

[0034] - the closure element is arranged such that it closes the bypass in the open position and such that the bypass remains open as long as the closure element is in the closed position.

[0035] Thus, when there is no filter cartridge in the filter housing, no fuel flows through the inlet port of the liquid filter, since all the fuel passes through the bypass directly to the further outlet port and back to the fuel tank.

[0036] - the filter element is rotatable within the filter housing between a first configuration in which it is held axially within the filter housing and a second configuration in which it can be removed axially from the filter housing.

[0037] - the filter element is attached to the filter housing using a bayonet mounting system.

[0038] The invention also relates to a vehicle comprising a liquid filter as described above.

[0039] Preferably, the outlet port is connected to an internal combustion engine of the vehicle and the further outlet port, if any, is connected to a fuel tank of the vehicle.

[0040] Further advantages and advantageous features of the invention are disclosed in the following description. BRIEF DESCRIPTION OF DRAWINGS

[0041] With reference to the appended drawings, below is a more detailed description of embodiments of the invention cited as an example. In these drawings:

[0042] Figure 1 is a perspective view of a vehicle, in particular a truck, comprising an internal combustion engine device and at least one fuel filter according to the invention;

[0043] Figure 2 is Figure 1a schematic view of an internal combustion engine arrangement of a vehicle comprising a main filter and a pre-filter, which can be considered as the first and second embodiments of the invention, respectively;

[0044] Figure 3 is a cross-sectional view of the main filter (first embodiment);

[0045] Figure 4 is a view according to Figure 3 is an enlarged view of block IV, wherein the leak-proof valve of the main filter is open;

[0046] Figure 5 is a view similar to Figure 4 , wherein the filter housing has been removed from the filter head, and wherein the leak-proof valve has been switched to the closed position;

[0047] Figure 6 is a cross-sectional view of the pre-filter (second embodiment);

[0048] Figure 7 is a detailed view of the leak-proof valve of the pre-filter, wherein said leak-proof valve is open;

[0049] Figure 8 is a view similar to Figure 7 , wherein the filter housing has been removed from the filter head, and wherein the leak-proof valve has been switched to the closed position;

[0050] Figure 9 is a bottom view of the filter head of the pre-filter; and

[0051] Figure 10 is a perspective view of the filter housing of the pre-filter. DETAILED DESCRIPTION

[0052] In the following detailed description of the drawings defined above, the same elements or elements that perform the same function can retain the same reference signs in order to simplify the understanding of the invention.

[0053] Figure 1 A vehicle 2, in particular a truck, is shown. The vehicle 2 comprises an internal combustion engine, in the drawings, in particular in Figure 2 , only the injection system 20 of the internal combustion engine is shown. As Figure 2 indicated above, the fuel circuit comprises a fuel tank 4, a pre-filter 6 (optional), a main filter 12 and a low pressure pump 10.

[0054] Generally, the fuel tank 4 is connected to a pre-filter 6 by a line 8. The pre-filter 6 comprises a tubular filter medium through which, in operation, fuel flows from the outside to the inside. This means that unfiltered fuel reaches a chamber around the filter medium and flows through the medium to reach a central chamber of the filter medium. A pump 10, known as a "low pressure pump", draws fuel from the outlet of the pre-filter 6 through a line 14 and pumps it to the inlet of a main filter 12.

[0055] Fuel leaves the filter 12 through a line 16 which carries it to the injection system 20 of the engine. Advantageously, the injection system 20 comprises pump injectors which draw fuel from the main filter 12 to the injection system 20, but alternatively a pump, commonly known as a "high pressure pump", can be used to pump fuel from the filter 12 to the injection system 20.

[0056] The system also comprises a line 22 to vent the portion of fuel which is not burnt during combustion. In fact, this unburnt portion of fuel is the fuel-gas mixture which comes out of the combustion cylinders of the engine. Moreover, a separation valve 24 separates the liquid from the gas: the liquid flows to the suction line 14 of the low pressure pump 10, while the gas returns to the tank 4.

[0057] As shown in Figure 3 The filter 12 comprises a filter housing 30 within which a filter element 32 (also known as "cartridge") is arranged. The filter housing 30, which is preferably made of plastic, is defined with a top opening.

[0058] The filter housing 30 is screwed under a filter head 36 (also known as "filter cap" or "filter casting"). The filter head 36 is thus fixed above the filter housing 30 and closes said top opening of the filter housing 30. The housing 30 can be unscrewed from the filter head 36 from below, which makes it possible to remove the filter element 32 and, if necessary, to replace it.

[0059] The filter head 36 is preferably made of aluminium and it also serves as a mounting bracket to fix the fuel filter 12 to the engine block.

[0060] In this document, we consider that the filter 6 or 12 can be of "cartridge construction" or of "spin-on construction". In "cartridge construction", the filter housing 30 is a permanent housing and only the filter element or cartridge 32 is replaced when necessary. In "spin-on construction", the filter housing 30 and the filter element 32 form one independent housing and element assembly which will be unscrewed from the filter head 36, discarded and replaced with a new housing and element assembly.

[0061] The filter element 32 comprises a tubular filter medium 38 arranged between two parallel plates 40 and 42. The filter medium 38 defines a central axis X38 (or axis of revolution). The filter medium 38 is made in a manner known per se from a pleated sheet.

[0062] By its tubular shape, the filter medium 38 defines an inner space or central space VI and an outer space V2 comprising the space above, below and around the medium 38.

[0063] The plate 42 is referred to as a "top end plate" since it is located in the upper part of the filter in the use configuration, while the plate 40 is referred to as a "bottom end plate" for the same reason. The plates 40 and 42 are made of liquid-tight material.

[0064] In the present example, the two plates 40 and 42 are disc-shaped and their maximum diameter (or outer diameter) is substantially equal to the maximum diameter (or outer diameter) of the filter medium 38.

[0065] The filter element 32 further comprises a central tube 33 (also referred to as "central pipe") coaxially arranged at the center of the filter medium 38, which means that the central axis X38 of the medium 38 coincides with the central axis X38 of the tube 33. In the present example, the inner space of the central tube 33 forms an inlet path for the liquid to be filtered.

[0066] In the present example, the wall of the tube 33 is complete, which means that the tube 33 does not comprise any radial hole. Thus, in operation, the liquid contained within the tube 33 does not escape radially to the outside of this tube.

[0067] During operation, the fuel flows radially from the outside to the inside through the filter medium 38. This means that the filter housing 30 delimits a first space VI for containing the flow of liquid to be filtered, which is delimited radially around the filter medium 38, and a second space V2 for containing the flow of filtered liquid, which is delimited radially inside the filter medium 38.

[0068] The top plate 42 comprises a liquid passage opening 60 (see Figure 4 ) communicating with the second space V2. This means that, during operation, the filtered liquid contained inside the filter medium 38 can directly escape upwards through the top plate opening 60 to the channel 16.

[0069] The filter head 36 delimits an inlet port (also referred to as "inlet hole" or "inlet opening") 19 particularly visible in Figure 5 and an outlet port (also referred to as "outlet hole" or "outlet opening") 20 particularly visible in Figure 4In particular, the outlet port 21 is visible. In this context, and according to the general definition, a "port" or "orifice" does not necessarily have to be interpreted as a hole with a circular cross section, it is more generally an opening, whatever its shape.

[0070] The inlet port 19 communicates with the first space VI, while the outlet port 21 communicates with the second space V2.

[0071] In Figure 3 and Figure 4 In the figures, the dashed arrows Al, A2, A3 and A4 indicate the passage route of the liquid in normal operation.

[0072] The central tube 33 and the bottom plate 40 are connected to each other in such a way that, in operation, the liquid escapes through the bottom plate 40 to the outside of the filter medium 38.

[0073] In the present example, the central tube 33 and the bottom plate 40 are two distinct parts. The central tube 33 is connected in a sealed manner to the hole of the bottom plate 40.

[0074] In this context, and according to the general definition, the fact that the tube 33 is "connected" to the plate 40 does not necessarily mean that the tube 33 and the plate 40 are made of two distinct pieces: in a variant not shown, the central tube 33 can be integral with the bottom plate 40, i.e. be a single piece.

[0075] The top plate 42 is defined with a central opening which forms an outlet path for the filtered liquid. This central opening opens into the central space of the medium 38. In other words, the central opening of the top plate directly communicates with the internal space of the filter medium 38, i.e. the filtered liquid inside the medium 38 can directly escape upwards through this opening of the top plate.

[0076] Moreover, the central tube 33 is set back radially from the inner wall of the filter medium 38.

[0077] In the present example, the central tube 33 is fixed, in particular clamped to one of the two plates 40 and 42, in particular to the bottom plate 40.

[0078] Advantageously, the central tube 33 passes through the top plate 42, i.e. the central tube 33 is housed within the said opening of the top plate 42, so that the filtered liquid passes between the tube 33 and the said opening of the top plate, and the tube 10 protrudes upwards compared to the rest of the filter element 32.

[0079] During operation, and as Figure 3As shown, the fuel to be filtered enters the filter housing 30 through the radial hole(s) extending through the central tube 33. This fuel then flows through the entire length of the tube 33 (arrow Al). This fuel then passes through the bottom plate 40 through the sealed connection between the tube 10 and the plate 8, flows up the side of the medium 38, and accumulates in the space around the filter medium 4 (arrow A2). The fuel then passes through the filter medium 38 in a direction that is substantially radial to the central axis X38 of the medium 38 (arrow A3). The filtered fuel then flows up the central tube 33, through the passage section between the tube 33 and the opening of the top plate, and joins the outlet channel (not shown) extending through the filter head 36 (see arrow A4).

[0080] In the present example, the central tube 33 has fins driving the flow of fuel in the helical direction around the central axis X38 (see arrow A4 in Figure 3 This has the advantage of directing the flow of filtered fuel to the top and creating a dynamic flow behavior. In other words, this avoids the fuel flowing down and accumulating in the lower part of the filter.

[0081] Typically, and as shown in Figure 4 the liquid to be filtered enters the filter housing 30 through a central passage, and the filtered liquid also exits the filter housing 30 through a central passage. Typically, this outlet passage is arranged coaxially around the inlet passage.

[0082] As shown in Figure 4 and Figure 5 The filter head 36 is particular in that it comprises a leak-proof valve 50 (also called "inlet valve") comprising a closing element 52 that can move between a closed position (as shown in Figure 5 in which the closing element 52 closes the inlet port 19, and an open position (as shown in Figure 4 in which the liquid can flow through the inlet port 19.

[0083] In the present example, and as is common for this type of valve, the closing element 52 of the valve 50 cooperates with a valve seat. This valve seat is part of the filter head 36.

[0084] Advantageously, this valve seat is made of rubber, which avoids the use of an additional sealing ring.

[0085] In addition, the filter 12 also comprises a pin 54 that is fitted on the filter element 32 and is configured to penetrate into the inlet port 19 in order to move the closing element 52 from the closed position to the open position.

[0086] In particular, the closure element 52 is axially movable, i.e. in a direction parallel to the axis X38. The closure element 52 is in a default closed position under the influence of gravity. When the pin 54 penetrates into the inlet port 19, it pushes the closure element 52 upwards, thereby opening the passage for liquid through the inlet port 19. When the filter housing 30 is removed, the pin 54 moves out of the inlet port 19 and the closure element 52 moves under the influence of gravity back to the closed position. Thus, the valve 50 prevents inflow of fuel through the inlet port 19, which means that no fuel will drip onto the floor or onto the operator when the filter element 32 is replaced.

[0087] In the present example, the closure element 52 is a plunger (or piston).

[0088] Generally, the pin 54 is arranged at the center of the top end plate 42. In the present example, the pin 54 extends axially upwards. The pin 54 protrudes upwards relative to the rest of the filter element 32.

[0089] In the example of the drawings, although not properly shown, the filter head 36 comprises a further outlet channel (not shown) which communicates with the return line 18. A de-aeration valve is preferably included in said further channel. As the name implies, the de-aeration valve opens to let gas (typically air) inside the filter housing flow back to the fuel tank and, once the filter housing is full of liquid, the de-aeration valve is closed. Since such de-aeration valves are well known in the art, they will not be described in further detail.

[0090] In the embodiment of the drawings, the filter head 36 delimits an inlet channel 37 which is arranged upstream of the inlet port 19.

[0091] Due to this leak-proof valve 50, the inlet port 19 is automatically closed when there is no filter element 32, because the closure element 52 will close the inlet port by default. Thus, if there is no filter element 32, 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, due to the lack of fuel supply, it will automatically stop after a short time. The same defect can be observed if the filter element in the system (i.e. in the filter housing 30) is not designed for this particular application (i.e. if the filter element is not provided with a pin 54). This is referred to as "no filter, no run".

[0092] In an alternative embodiment, not shown, the filter head 36 delimits a further outlet port (not shown) and a bypass (not shown) extending between the inlet channel 37 and said further outlet port. In this case, the closure element 52 is arranged such that it, in the open position (i.e. when the pin 54 is in the inlet port 19), opens the bypass and, in the closed position (i.e. when the pin 54 is not in the inlet port 19), closes the bypass. Figure 4) closing said bypass and, as long as this closing element is in the closed position Figure 5 ), said bypass is opened.

[0093] Figures 6 to 8 A pre-filter 6 is shown, which can be considered as another embodiment of the application. For the sake of brevity, only the differences with the main filter 12 are described here.

[0094] 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.

[0095] Another difference is that the closing element 52 is a ball, preferably made of plastic.

[0096] Furthermore, the filter head 36 comprises indexing means 100 for guiding the pin 54 towards the inlet port 19 when screwing the filter housing 30 to the filter head 36, until the pin 54 reaches a configuration in which it is axially aligned with the first port 19, i.e. an aligned configuration.

[0097] In the present example, the filter element 32 is rotationally fixed with the filter housing 30 and the pin 54 is part of a ring 56 rotatably mounted on the top end plate 42 of the filter element 32. This means that the ring 56 is free to rotate with respect to the top plate 42. Preferably, the ring 56 is coaxially arranged on the top surface of the top plate 42. Typically, the ring 56 is clipped on the top plate 42. However, any other means of attaching the ring 56 to the top plate 42 can be used.

[0098] In an alternative embodiment, not shown, the filter element 32 is rotationally movable with respect to the filter housing 30. In this case, there will be no ring 56: the pin 54 will be part of the top end plate 42 of the filter element 32.

[0099] As can be gathered from Figure 9 , the indexing means 100 comprise a guiding surface in the form of an elliptical surface. This guiding surface is inclined with respect to a plane perpendicular to the central axis of the filter 12, i.e. the axis X38. In other words, this guiding surface corresponds to the intersection of a tube with a plane that is not perpendicular to the central axis of said tube (oblique plane).

[0100] This guiding surface is designed to guide the pin 54 towards the inlet port 19 when the filter housing 30 is assembled at the bottom of the filter head 36.

[0101] The indexing device 100 comprises a wall 102 which fits on the filter head 36 and extends substantially parallel to the longitudinal axis X38. The wall 102 forms an abutment which is configured to cooperate with the pin 54.

[0102] The wall 102 is a protrusion from the filter head 36 which cooperates with the pin 54 to place and maintain the pin 54 in the above-mentioned aligned configuration. According to one aspect of the application, the wall 102 is a profiled part which extends substantially parallel to the longitudinal axis X38.

[0103] Generally, when it is necessary to replace the filter element 32, the operator first removes the filter element 32 by unscrewing the filter housing 30 from the filter head 36. When the operator starts to unscrew the filter head 36, the rotating ring 56 remains stationary because the pin 58 is prevented from rotating as it is engaged in the inlet port 19 which acts as a receiving hole. Once the pin 54 is out of the port 19, its rotation is no longer blocked and it rotates together with the filter element 32.

[0104] Afterwards, a new filter housing is installed under the filter head. The filter housing 30 can be kept ("cartridge" design) or thrown away ("spin-on" design).

[0105] When the operator starts to screw the filter housing 30 around or inside the filter head 36, the pin 54 abuts against the guiding surface 100 of the filter head 36 (it is not necessary to orient the pin 54 exactly in front of the inlet port 19). Then, the screwing movement (which comprises a rotation and a translation) forces the pin 54 to move along the guiding surface 100.

[0106] The pin 54 can move in the same direction as the screwing movement, or in the opposite direction, depending on its position against the filter head surface 100. Generally, if the pin 54 is close to the hole 19, but the screwing rotation movement tends to move the pin away from the hole 19, the inclined nature of the guiding surface 100 will prevent the pin 54 from moving in that direction and will force the pin 54 to move in the other direction and reach the hole 19. This is made possible thanks to the fact that the rotating ring 56 to which the pin 54 belongs can rotate relative to the top plate 42. Then, even if the top plate 42 rotates in one direction, the pin 54 can rotate in the other direction.

[0107] Therefore, it should be understood that the pin 54 is automatically oriented towards its final position during the assembly operation, which means that the operator does not have to orient the filter element 32 in such a way that the pin 54 penetrates into the inlet hole 19.

[0108] When the pin 54 reaches the hole 19, the ring 56 stops rotating. However, the filter housing 30 keeps turning until the screwing movement is completed. By making the screwing movement, the pin 54 is pushed into the hole 19 to reachFigure 7 the position shown.

[0109] One advantage of this particular filter design is that if someone tries to replace the filter element 32 with a filter element having a different design, the valve 50 will remain closed and no fuel will flow in the filter housing 30. This particular design therefore ensures that the engine will not run if an inappropriate filter element is assembled within the housing 30 (or if there is no filter): this safety feature is known as "no filter, no run", as mentioned above.

[0110] In combination Figure 10 , the filter element 32 can be rotated within the filter housing 30 between a first configuration (not shown) in which the filter element 32 is held axially within the filter housing 30 and a second configuration (shown in Figure 10 ) in which the filter element 32 can be removed axially from the filter housing 30.

[0111] Generally, the filter element 32 is attached to the filter housing 30 using a bayonet mounting system. This bayonet mounting system comprises at least one L-shaped locking groove (preferably a plurality of locking grooves 70 provided on the radially inner surface of the filter housing 30) and at least one complementary radial tooth (preferably two complementary radial teeth provided on the radially outer surface of the filter element 32). Said two radial teeth can be seen in Figure 10 .

[0112] This bayonet mounting system is particularly advantageous in a configuration in which only the filter cartridge needs to be replaced (cartridge configuration). Indeed, after the filter housing has been removed from the filter head, the operator first empties the remaining fuel of said housing into a first dedicated bin (not shown), secondly moves the filter cartridge relative to said housing to enter the second configuration (shown in Figure 10 ). The operator can then simply remove the filter cartridge from said housing by simply orienting the opening of the filter housing towards the ground: the filter cartridge slides out of said housing by gravity into a second dedicated bin (not shown). This makes it possible to recycle both the fuel and the filter cartridge, which is more environmentally friendly than actually disposing of them.

[0113] In a variant not shown, a clamping device can be used instead of said bayonet mounting system to attach the filter element 32 within the filter housing 30. Generally, the filter element 32 will comprise one or more clips that engage within corresponding recesses defined on the filter housing 30. Once the filter housing 30 has been detached from the filter head 36, the operator can easily separate the filter element 32 from the housing 30 using a screwdriver or the like in order to unfasten the filter element 32 from the filter housing 36.

[0114] Preferably, the filter head 36 comprises a spill prevention ring 104 arranged coaxially around said guiding surface. This spill prevention ring 104 makes it possible to fill the dead space between the filter head 36 and the filter cartridge 32: thus, when the filter housing 30 is removed from the filter head 36, the fuel trapped between the spill prevention ring 104 and the filter cartridge 32 falls into the filter housing 30, which means that there is no fuel spillage once the filter housing 30 is removed.

[0115] Preferably, the spill prevention ring 104 is provided with ribs 106 which reinforce its structure.

[0116] In the present embodiment, for the main filter 12, the outlet port 21 is arranged at the center of the filter head 36, which means that the filtered liquid flows out of the liquid filter through the center of the filter.

[0117] In a variant not shown, the filter housing 30 would be screwed on the filter head 36 through the top, which means that in the assembled configuration, the filter head 36 is located below the filter housing 30. In this embodiment, a return member, for example a spring, would be used to push the closure element 52 upwards and maintain it in the closed position.

[0118] It goes without saying that the application is not limited to the above-described embodiments which are given by way of example; it includes all variants.

[0119] It will be understood that the application is not limited to the embodiments described above and shown in the drawings; on the contrary, a person skilled in the art will recognize many modifications and variants within the scope of the appended claims.

Claims

1. A liquid filter (6, 12) for a vehicle, said liquid filter comprising: - Filter head (36), which defines an inlet port (19) and an outlet port (21); - A filter housing (30) is screwed below the filter head (36) and houses a filter element (32) centered on a central axis (X38), the filter element comprising a filter medium (38), a top end plate (42), and a bottom end plate (40). The filter housing (30) defines a first space and a second space. The first space is used to accommodate the liquid flow to be filtered. The first space is radially defined around the filter medium (38) and communicates with the inlet port (19). The second space is used to accommodate the filtered liquid flow. The second space is radially defined inside the filter medium (38) and communicates with the outlet port (21). The filter head (36) includes a leak-proof valve (50), which includes a closing element (52) movable between a closed position and an open position. In the closed position, the closing element seals the inlet port (19), and in the open position, liquid can flow through the inlet port (19). The liquid filter (6, 12) also includes a pin (54) fitted onto the filter element (32), and the pin is configured to... The pin (54) is inserted into the inlet port (19) to move the closing element (52) from the closed position to the open position. The pin (54) extends axially upward, and the filter head (36) includes a valve seat configured to cooperate with the closing element (52) to close the inlet port (19). The closing element (52) is held in the closed position by gravity by default, and automatically returns to the closed position by gravity when the pin is removed from the inlet port (19). The filter head (36) is characterized in that it defines an inlet channel (37) and another outlet port as well as a bypass, the inlet channel (37) being arranged upstream of the inlet port (19), the bypass extending between the inlet channel and the other outlet port, and the closing element (52) being arranged such that the closing element (52) closes the bypass in the open position, and such that: as long as the closing element is in the closed position, the bypass is opened, so that when there is no filter element in the filter housing, no fuel flows through the inlet port of the liquid filter, because all the fuel flows directly through the bypass to the other outlet port and back to the vehicle's fuel tank.

2. The liquid filter according to claim 1, characterized in that, The filter head (36) also includes a shifting device (100) for guiding the pin (54) toward the inlet port (19) when the filter housing (30) is screwed onto the filter head (36) until the pin (54) reaches a configuration in which the pin (54) is axially aligned with the inlet port (19).

3. The liquid filter according to claim 2, characterized in that, The filter element (32) is rotatably fixed together with the filter housing (30), and the pin (54) is part of a ring (56) rotatably mounted on the top end plate (42) of the filter element (32).

4. The liquid filter according to claim 2, characterized in that, The filter element (32) is rotatably movable relative to the filter housing (30), and the pin (54) is part of the top end plate (42) of the filter element (32).

5. The liquid filter according to any one of claims 1-4, characterized in that, The pin (54) is arranged eccentrically relative to the central axis.

6. The liquid filter according to any one of claims 1-4, characterized in that, The pin (54) is located at the center of the top end plate.

7. The liquid filter according to any one of claims 1-4, characterized in that, The closing element (52) is a ball or a plunger.

8. The liquid filter according to any one of claims 1-4, characterized in that, The filter element (32) is rotatable within the filter housing (30) between a first configuration and a second configuration, in which the filter element is axially held within the filter housing (30) and in the second configuration, the filter element is axially removable from the filter housing (30).

9. The liquid filter according to claim 8, characterized in that, The filter element (32) is attached to the filter housing (30) using a bayonet mounting system (70).

10. The liquid filter according to any one of claims 1-4, characterized in that, The liquid filters (6, 12) are fuel filters.

11. A vehicle (2), characterized in that, The vehicle includes a liquid filter (6, 12) according to any one of claims 1-10.

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