Filter module for fluid filtration

Abstract

The invention relates to a filter module (10) for fluid filtration, in particular for fuel filtration, comprising a filter medium (14) through which a fluid can flow, a drivable conveying device (16) for conveying the fluid through the filter module (10) and a pressure limiting device (22) for limiting the fluid pressure of the fluid discharged from the filter module (10) to an operating pressure limit value.

Description

The invention relates to a filter module for fluid filtration, in particular for fuel filtration, having a filter medium through which a fluid can flow, a drivable conveying device for conveying the fluid through the filter module, and a pressure limiting device for limiting the fluid pressure of the fluid discharged from the filter module to an operating pressure limit value.The invention further relates to a fluid supply system for supplying a fluid into a fluid utilization system, having a fluid tank for storing the fluid, a supply line leading to the fluid utilization system, a filter module arranged along the supply line for filtering the fluid, and a tank return line for returning the fluid from the supply line into the fluid tank and for venting at least part of the fluid supply system.The invention furthermore relates to a method for operating a fluid supply system, having the steps of: filtering a fluid by means of a filter medium, through which the fluid can flow, of a filter module of the fluid supply system, and conveying the fluid through the filter module by means of a drivable conveying device of the fluid supply system, wherein the fluid pressure of the fluid discharged from the filter module is limited to an operating pressure limit value by means of a pressure limiting device of the filter module in a continuous operating state of the fluid supply system.In a variety of filtration applications, fluid pressure is required to be limited to an operating pressure limit during operation of the higher level system so that damage to pressure sensitive components and / or performance of pressure sensitive control procedures is not compromised. In particular in systems with a tank return line for returning the fluid into a fluid tank and for venting the system, a fluid pressure which is above the operating pressure limit value is frequently required for the fluid return and / or venting. Because of the pressure limitation to the operating pressure limit value, such fluid pressures cannot be readily generated by the drivable conveying device of the filter module, so that the fluid recirculation and / or venting has hitherto been associated with a considerable outlay.The object on which the invention is based is to make possible the fluid recirculation and venting in a fluid supply system by means of the drivable conveying device of the filter module.The object is achieved by a filter module of the type mentioned at the beginning, wherein the filter module according to the invention comprises a pressure release device for temporarily cancelling a limitation of the fluid pressure of the fluid discharged from the filter module caused by the pressure limiting device.The invention makes use of the finding that by cancelling the pressure limitation, the setting of a pressure level is temporarily made possible, which pressure level allows the fluid to be returned to a fluid tank and at least a part of the fluid supply system to be vented. The limitation of the fluid pressure emanating from the pressure limiting device is consequently temporarily bypassed or deactivated by the pressure release device. The operating pressure limit value can be adapted, for example, to the load capacity of a membrane which is acted upon with the fluid pressure in a fluid supply system comprising the filter module or a fluid utilization system connected to the fluid supply system.The delivery device can be a pump, for example. The conveying device can have an electric drive. The conveying device can alternatively have a hydraulic or pneumatic drive.The filter medium is preferably arranged upstream of the conveying device in the flow direction of the fluid. The filter medium can be configured circumferentially and / or form a pleated round filter. The filter medium is preferably a component of an exchangeable filter insert of the filter module. The filter insert can be configured to implement a single-stage or a multistage filtration.In a preferred embodiment of the filter module according to the invention, the pressure limiting device comprises a return line which connects a line section located behind the conveying device in the flow direction of the fluid to a line section located in front of the conveying device in the flow direction of the fluid in a fluid-conducting manner. The return line consequently connects a line section on the pressure side of the conveying device to a line section on the suction side of the conveying device. The line section located upstream of the conveying device in the flow direction of the fluid is preferably located downstream of the filter medium in the flow direction of the fluid. The conveying device and the return line are consequently located on the clean side of the filter module and are flowed through by a fluid filtered by the filter module.Furthermore, a filter module according to the invention is advantageous in which the pressure limiting device comprises a return valve, which is preferably arranged along the return line and / or is configured to block the return line. The return valve of the pressure limiting device preferably has a valve spring. The valve spring may be a compression spring or a tension spring.In a further preferred embodiment of the filter module according to the invention, the return valve of the pressure limiting device is configured to automatically block the return line if the fluid pressure upstream of the return valve falls below the operating pressure limit value. Alternatively or additionally, the return valve of the pressure limiting device is configured to open when the fluid pressure upstream of the return valve rises above the operating pressure limit value. By blocking the return line, the pressure limitation to the operating pressure limit value is canceled. Such a pressure limitation is not required during operation of the fluid supply system or during operation of the fluid use system if the fluid pressure is below the operating pressure limit value. By opening the return valve of the pressure limiting device, the flow path through the return line is opened, so that a pressure limitation occurs due to the flow resistance and the circulation conveyance of the fluid. The return valve of the pressure limiting device can be designed as a shut-off valve or as an expansion valve.In a further preferred embodiment of the filter module according to the invention, the pressure release device comprises a pressure release valve which is arranged along the return line and is configured to block the return line and / or to reduce the fluid pressure and / or the volume flow in the return line. The pressure release valve of the pressure release device preferably comprises a valve spring. The valve spring may be a compression spring or a tension spring.In another preferred embodiment of the filter module according to the invention, the pressure release valve of the pressure release device is configured to block the return line upon actuation and / or to reduce the fluid pressure and / or the volume flow in the return line. Alternatively or additionally, the pressure release valve of the pressure release device is configured to open automatically when the actuation is canceled. In the unactuated state, the pressure release valve of the pressure release device is open, so that the return line is not blocked by the pressure release valve. The pressure release valve of the pressure release device can be designed as a shut-off valve or as an expansion valve.Furthermore, a filter module according to the invention is preferred, in which the pressure release valve of the pressure release device comprises an actuating member which can be manually actuated by a user. The actuating member can be press-actuatable and / or pull-actuatable, for example. Alternatively or additionally, the actuating member can also be actuatable by a rotational, pivoting and / or folding movement. The filter module can comprise a fluid chamber with a transparent chamber wall, so that it can be detected by way of a visual check whether air still to be discharged from the system is present in the fluid chamber. The venting process triggered by the actuation of the actuating member can thus be maintained until air is no longer visible in the fluid chamber with transparent chamber wall. In this case, the actuation of the actuating member can be canceled, so that the venting process is interrupted, so that the pressure limitation by the pressure limiting device is also no longer canceled.Furthermore, a filter module according to the invention is preferred, in which the pressure release device has a locking device, by means of which the actuating member of the pressure release valve can be locked in order to prevent unintentional actuation. The locking device can be, for example, a rotary lock which requires a rotary movement of the actuating member to release the actuating movement of the actuating member. The locking device may also comprise a locking element, such as a locking pin or a locking bolt, by means of which the actuating member is secured. Alternatively or in addition to the locking device, the pressure release device can comprise a protective cover, by means of which the actuating element of the pressure release valve is covered in order to prevent unintentional actuation.In a further preferred embodiment of the filter module according to the invention, the pressure release valve of the pressure release device can be actuated by means of a valve control. The pressure release valve can in this case be, for example, an actuatable solenoid valve. For controlling the pressure release valve, the pressure release valve can be connected, for example, to a control device of the filter module or to a control device of the fluid supply system or to a control device of the fluid utilization system.In a further preferred embodiment of the filter module according to the invention, the return valve of the pressure limiting device is arranged behind the pressure release valve of the pressure release device in the flow direction of the fluid. The pressure release valve of the pressure release device is preferably configured to cause the return valve of the pressure limiting device to close upon actuation. By actuating the pressure release valve, the pressure upstream of the return valve falls below the operating pressure limit value, so that the return valve of the pressure limiting device closes automatically. Due to the blocked return line, no pressure limitation takes place.In an advantageous development of the filter module according to the invention, the return valve of the pressure limiting device has a shut-off body and the pressure release valve of the pressure release device has a shut-off body. The shut-off body of the return valve of the pressure limiting device and the shut-off body and the pressure release valve of the pressure release device have opposite closing directions. Alternatively or additionally, the shut-off body of the return valve of the pressure limiting device and the shut-off body of the pressure release valve of the pressure release device have opposite opening directions. Preferably, a ring structure carries on one side the valve seat of the return valve of the pressure limiting device and on an opposite side the valve seat of the pressure release valve of the pressure releasing device.The object on which the invention is based is furthermore achieved by a fluid supply system of the type mentioned at the beginning, wherein the filter module of the fluid supply system according to the invention is designed according to one of the embodiments described above. With regard to the advantages and modifications of the fluid supply system according to the invention, reference is thus made first to the advantages and modifications of the filter module according to the invention.The fluid supply system may be, for example, a fuel supply system for supplying fuel into an injection system of an internal combustion engine. Preferably, the filter module and a part of the feed line can be vented via the tank return line.In a preferred embodiment, the fluid supply system according to the invention has a return valve which is arranged along the tank return line. The return valve is preferably configured to open automatically when the fluid pressure upstream of the return valve rises above a venting pressure limit. The return of the fluid from the feed line into the fluid tank and the venting of at least a part of the fluid feed system can thus be caused by a pressure increase upstream of the return valve above the venting pressure limit value. The increase in pressure upstream of the return valve above the venting pressure limit value can be achieved by cancelling the limitation of the fluid pressure caused by the pressure limiting device.In a further preferred embodiment of the fluid supply system, the venting pressure limit value is higher than the operating pressure limit value, so that the return valve is closed as long as the fluid pressure is limited to the operating pressure limit value by the pressure limiting device. The control pressure of the return valve is consequently higher than the control pressure of the return valve of the pressure limiting device.In a further preferred embodiment of the fluid supply system according to the invention, the conveying device is configured to provide a conveying capacity during operation of the fluid supply system, which at least temporarily requires a limitation of the fluid pressure of the fluid discharged from the filter module by means of the pressure limiting device to the operating pressure limit value and which, when the limitation of the fluid pressure caused by the pressure limiting device is canceled by the pressure releasing device, leads to the fluid pressure upstream of the return valve rising above the venting pressure limit value and thus to the opening of the return valve. When the return valve is opened, the fluid from the feed line returns to the fluid tank and at least a part of the fluid feed system is vented.Furthermore, a fluid supply system according to the invention is preferred, which has a further drivable conveying device. The further drivable conveying device is arranged along the feed line and outside the filter module. Preferably, the further drivable conveying device is configured to convey the fluid to the fluid utilization system. The further conveying device can be a pump. The further conveying device can have an electric drive. The further conveying device can alternatively have a hydraulic or pneumatic drive.The object on which the invention is based is furthermore achieved by a method of the type mentioned at the beginning, wherein the limitation of the fluid pressure of the fluid discharged from the filter module caused by the pressure limiting device is temporarily canceled by means of a pressure release device of the filter module in a venting operating state. By means of the method, a fluid supply system according to one of the above-described embodiments is preferably operated. With regard to the advantages and modifications of the method according to the invention, reference is thus made first to the advantages and modifications of the fluid supply system according to the invention.In a preferred embodiment of the method according to the invention, the return valve of the pressure limiting device is arranged behind a pressure release valve of the pressure release device in a return line of the filter module in the flow direction of the fluid. The pressure release valve of the pressure release device is actuated in the venting operating state and causes the return valve of the pressure limiting device to close.The method according to the invention is further advantageously further developed in that the conveying device, in the continuous operating state of the fluid supply system, produces a conveying capacity which at least temporarily causes a limitation of the fluid pressure of the fluid discharged from the filter module to the operating pressure limit value by means of the pressure limiting device. In the venting operating state of the fluid supply system, the delivery device provides a delivery rate which, when the limitation of the fluid pressure caused by the pressure limiting device is canceled by the pressure release device, leads to the fluid pressure upstream of a return valve of the fluid supply system rising above a venting pressure limit value and thus to the opening of the return valve.Preferred embodiments of the invention are explained and described in more detail below with reference to the attached drawings. The following are shown: FIG. 1 shows a schematic illustration of a fluid supply system according to the invention, which is in a continuous operating state; FIG. 2 shows the fluid supply system depicted in FIG. 1 after setting a venting operating state in a schematic illustration; FIG. 3 shows a filter module according to the invention in a sectional illustration; FIG. 4 shows a section of the return line of the filter module depicted in FIG. 3 during the limitation of the fluid pressure to an operating pressure limit value; FIG. 5 shows a detailed illustration of the return valve and the pressure release valve of the filter module depicted in FIG. 4 ; FIG. 6 shows a section of the return line of the filter module depicted in FIG. 3, during which the limitation of the fluid pressure to an operating pressure limit value is canceled; and FIG. 7 shows a detailed illustration of the return valve and of the pressure release valve of the filter module depicted in FIG. 6.FIGS. 1 and 2 show a fluid supply system 100 for supplying a fluid into a fluid utilization system 200. The fluid supply system 100 is a fuel supply system, and the fluid use system 200 is an injection system of an internal combustion engine.The fluid supply system 100 comprises a fluid tank 102 for storing the fluid embodied as fuel. In addition, the fluid supply system 100 comprises a supply line 104 a- 104 cthat leads to the fluid use system 200. The feed line 104 a- 104 ccomprises at least three line segments, wherein a filter module 10 for filtering the fluid is arranged between the line segments 104 a, 104 b. A tank return line 106 branches off from the line segment 104 bof the feed line, which serves for returning the fluid from the feed line 104 a- 104 cto the fluid tank 102 and for venting a part of the fluid feed system 100. The filter module 10 and a part of the feed line 104 a- 104 cmay be vented via the tank return line 106.A conveying device 110 is arranged between the line segments 104 b, 104 cof the feed line. The delivery device 110 is a pump and serves to deliver the fluid to the fluid usage system 200. The conveying device 110 is driven by an electric drive 112.The fluid usage system 200 is connected to a system return line 202, via which the fluid can be fed from the fluid usage system 200 back into the fluid tank 102.The filter module 10 serves for fuel filtration and has a fluid inlet 12 via which the fluid can flow into the filter module 10. The fluid flowing into the filter module 10 via the fluid inlet 12 is first conducted through a filter medium 14, through which the fluid can flow and serves for filtering the fluid. The filter module 10 further comprises a conveying device 16 designed as a pump for conveying the fluid through the filter module 10. The filter medium 14 is located on the suction side of the conveying device 16. The filter module 10 further comprises a fluid outlet 20, via which the fluid filtered in the filter module 10 can be discharged from the filter module 10.The filter module 10 comprises a pressure limiting device 22 for limiting the fluid pressure of the fluid discharged from the filter module 10 to an operating pressure limit value. The pressure limiting device 22 comprises a return line 26 which connects a line section 24 blocated behind the conveying device 16 in the flow direction of the fluid to a line section 24 alocated in front of the conveying device 16 in the flow direction of the fluid in a fluid-conducting manner. The line section 24 bis located on the pressure side of the conveying device. The line section 24 ais located on the suction side of the conveying device 16.The pressure limiting device 22 of the filter module 10 has a return valve 28, which is arranged along the return line 26. The return line 26 can be blocked by means of the return valve 28. The return valve 28 of the pressure limiting device 22 is configured to automatically block the return line 26 if the fluid pressure upstream of the return valve 28 falls below the operating pressure limit value. Further, the recirculation valve 28 is configured to open when the fluid pressure upstream of the recirculation valve 28 increases above the operating pressure limit. The return valve 28 of the pressure limiting device 22 is a pressure-controlled shut-off valve.The filter module 10 further comprises a pressure release device 30 for temporarily cancelling a limitation of the fluid pressure of the fluid discharged from the filter module 10 caused by the pressure limiting device 22. The pressure release device 30 comprises a pressure release valve 32 which is arranged along the return line 26. By means of the pressure release valve 32, the return line 26 can be blocked. Alternatively, the fluid pressure and / or the volume flow in the return line 26 can be reduced by means of the pressure release valve 32. The pressure release valve 32 of the pressure release device 30 is configured to block the return line 26 upon actuation. Alternatively, the pressure release valve 32 of the pressure release device 30 can be configured to reduce the fluid pressure and / or the volume flow in the return line 26 when actuated. Further, the pressure release valve 32 of the pressure release device 30 is configured to automatically open when the operation is canceled.A return valve 108 of the fluid supply system 100 is arranged along the tank return line 106. The return valve 108 automatically opens when the fluid pressure upstream of the return valve 108 increases above a bleed pressure limit. The bleed pressure limit is higher than the operating pressure limit, so that the return valve 108 is closed as long as the fluid pressure is limited to the operating pressure limit by the pressure limiter 22.FIG. 1 shows a steady state operation of the fluid delivery system 100 in which the pressure release valve 32 of the pressure release device 30 is in an unactuated state. In the unactuated state, the pressure release valve 32 is opened, so that the fluid pressure upstream of the return valve 28 is above the operating pressure limit value due to the delivery capacity of the delivery device 16. Thus, the return valve 28 is also opened, thereby releasing the flow path along the return line 26. Because the fluid pressure is limited to the operating pressure limit, the fluid pressure upstream of the return valve 108 is below the bleed pressure limit. Because the fluid pressure upstream of the return valve 108 is below the bleed pressure limit, the return valve 108 is closed and the tank return line 106 is blocked.In the venting operating state shown in FIG. 2, the pressure release valve 32 of the pressure release device 30 is in an actuated state. The pressure release valve 32 of the pressure release device 30 is configured to block the return line 26 upon actuation. Because the return line 26 is blocked by the pressure release valve 32, the pressure upstream of the return valve 28 also falls below the operating pressure limit value, as a result of which the return line 26 is additionally blocked by the return valve 28.The conveying device 16 of the fluid supply system 100 is configured to provide a conveying capacity during operation of the fluid supply system 100, which at least temporarily requires a limitation of the fluid pressure of the fluid discharged on the filter module 10 to the operating pressure limit value by means of the pressure limiting device 22. When the limitation of the fluid pressure caused by the pressure limiting device 22 is canceled by the pressure release device 30, the delivery rate of the delivery device 16 leads to the fluid pressure upstream of the return valve 108 rising above the venting pressure limit value and thus to the opening of the return valve 108. Opening the return valve 108 returns fluid from the supply line 104a-104c to the fluid tank 102. Further, a part of the fluid supply system 100 is exhausted.FIG. 3 shows a filter module 10 which is designed as a single-stage filter module with only one filter stage. The filter medium 14 is configured circumferentially and forms a pleated round filter. The fluid flows through the filter medium 14 from the outside to the inside from a raw side 34 to a clean side 36. The line section 24 aducing to the conveying device 16 is thus located on the clean side 36 of the filter module 10.The filter module 10 comprises a multi-part housing 38, wherein the filter medium 14 is arranged in a cup-shaped housing part which is screwed into a base part of the housing 38.The pressure release valve 32 of the pressure release device 30 comprises an actuating member 40 which can be manually actuated by a user. The valve spring 42 of the pressure release valve 32 is a compression spring, so that the actuator 40 is press-operable. The filter module 10 can comprise a fluid chamber with a transparent chamber wall, so that it can be detected by way of a visual check whether air still to be discharged is located in the fluid chamber. In this case, the actuating member 40 can be pressed until air to be discharged is no longer visible in the fluid chamber.FIGS. 4 and 5 show the pressure release valve 32 of the pressure release device 30 in an unactuated state. In the unactuated state, the shut-off body 44 is pushed away from the valve seat 50 by the valve spring 42. Furthermore, the shut-off body 46 of the return valve 28 is pushed away from the valve seat 52 by the valve spring 48. In the illustrated state, the return line 26 is consequently released. A ring structure supports on one side the valve seat 52 of the return valve 28 and on an opposite side the valve seat 50 of the pressure release valve 32.FIGS. 6 and 7 show an operating state in which the pressure release valve 32 is operated. In the actuated state of the pressure release valve 32, the shut-off body 44 rests on the valve seat 50, so that the return line 26 is blocked. The blocking of the return line 26 also causes a movement of the blocking body 46 of the return valve 28 in the direction of the valve seat 52. The valve spring 48 of the return valve 28 is also a compression spring. Consequently, the shut-off body 46 of the return valve 28 of the pressure limiting device 22 and the shut-off body 44 of the pressure release valve 32 of the pressure release device 30 have opposite closing directions. Consequently, the shut-off body 46 of the return valve 28 of the pressure limiting device 22 and the shut-off body 44 of the pressure release valve 32 of the pressure release device 30 also have opposite opening directions.The pressure release device 30 may comprise a locking device, not shown, by means of which the actuating member 40 of the pressure release valve 32 may be lockable in order to prevent unintentional actuation.Reference numerals denote reference numerals10 Filter module 12 Fluid inlet 14 Filter medium 16 Conveying device 18 Drive 20 Fluid outlet 22 Pressure limiting device 24 a, 24 bPipe sections 26 Return line 28 Return valve 30 Pressure release device 32 Pressure release valve 34 Raw side 36 Clean side 38 Housing 40 Actuating member 42 Valve spring 44 Shut-off body 46 Shut-off body 48 Valve spring 50 Valve seat 52 Valve seat 100 Fluid supply system 102 Fluid tank 104 a- 104 cFeeding line 106 Tank return line 108 Return valve 110 Conveying device 112 Drive 200 Fluid use system 202 System return line

Claims

Filter module (10) for fluid filtration, in particular for fuel filtration, having - a filter medium (14) through which a fluid can flow; - a drivable conveying device (16) for conveying the fluid through the filter module (10); and - a pressure limiting device (22) for limiting the fluid pressure of the fluid discharged from the filter module (10) to an operating pressure limit value; characterized bya pressure release device (30) for temporarily cancelling a limitation, caused by the pressure limiting device (22), of the fluid pressure of the fluid discharged from the filter module (10).Filter module (10) according to Claim 1, characterized in that the pressure limiting device (22) comprises a return line (26) which connects a line section (24b) located behind the conveying device (16) in the flow direction of the fluid to a line section (24a) located in front of the conveying device (16) in the flow direction of the fluid in a fluid-conducting manner.Filter module (10) according to claim 2, characterised in that the pressure limiting device (22) comprises a return valve (28), which is preferably arranged along the return line (26) and / or is configured to block the return line (26).Filter module (10) according to claim 3, characterised in that the return valve (28) of the pressure limiting device (22) is configured to - automatically block the return line (26) if the fluid pressure upstream of the return valve (28) falls below the operating pressure limit value; and / or - open if the fluid pressure upstream of the return valve (28) rises above the operating pressure limit value.Filter module (10) according to one of Claims 2 to 4, characterized in that the pressure release device (30) comprises a pressure release valve (32) which is arranged along the return line (26) and / or is configured to block the return line (26) and / or to reduce the fluid pressure and / or the volume flow in the return line (26).Filter module (10) according to claim 5, characterised in that the pressure release valve (32) of the pressure release device (30) is configured to - block the return line (26) upon actuation and / or to reduce the fluid pressure and / or the volume flow in the return line (26); and / or - open automatically when the actuation is canceled.Filter module (10) according to claim 5 or 6, characterised in that the pressure release valve (32) of the pressure release device (30) comprises an actuating member (40) which can be actuated manually by a user, in particular can be actuated under pressure and / or actuated under tension.Filter module (10) according to claim 7, characterised in that the pressure release device (30) has a locking device, by means of which the actuating member (40) of the pressure release valve (32) can be locked in order to prevent unintentional actuation.Filter module (10) according to one of Claims 5 to 8, characterized in that the pressure release valve (32) of the pressure release device (30) can be actuated by means of a valve controller for actuation.Filter module (10) according to one of Claims 5 to 9, characterized in that the return valve (28) of the pressure limiting device (22) is arranged downstream of the pressure release valve (32) of the pressure release device (30) in the direction of flow of the fluid, wherein the pressure release valve (32) of the pressure release device (30) is preferably designed to cause the return valve (28) of the pressure limiting device (22) to close on actuation.Filter module (10) according to one of Claims 5 to 10, characterized in that the return valve (28) of the pressure limiting device (22) has a shut-off body (46) and the pressure release valve (32) of the pressure release device (30) has a shut-off body (44), wherein the shut-off body (46) of the return valve (28) of the pressure limiting device (22) and the shut-off body (44) of the pressure release valve (32) of the pressure release device (30) have opposite closing directions, and / or wherein the shut-off body (46) of the return valve (28) of the pressure limiting device (22) and the shut-off body (44) of the pressure release valve (32) of the pressure release device (30) have opposite opening directions.A fluid supply system (100) for supplying a fluid into a fluid use system (200), comprising - a fluid tank (102) for storing the fluid; - a supply line (104a-104c) leading to the fluid use system (200); - a filter module (10) arranged along the supply line (104a-104c) for filtering the fluid; and - a tank return line (106) for returning the fluid from the supply line (104a-104c) into the fluid tank (102) and for venting at least a part of the fluid supply system (100); characterized in that the filter module (10) is configured according to one of the preceding claims.The fluid delivery system (100) of claim 12, characterized bya return valve (108) disposed along the tank return line (106), the return valve (108) configured to automatically open when the fluid pressure upstream of the return valve (108) increases above a venting pressure limit.Fluid supply system (100) according to claim 13, characterised in that the venting pressure limit value is higher than the operating pressure limit value, so that the return valve (108) is closed as long as the fluid pressure is limited to the operating pressure limit value by the pressure limiting device (22).Fluid supply system (100) according to Claim 13 or 14, characterized in that the delivery device (16) is configured to provide, during operation of the fluid supply system (100), a delivery rate which at least temporarily requires a limitation of the fluid pressure of the fluid discharged from the filter module (10) by means of the pressure limiting device (22) to the operating pressure limit value and which, when the limitation of the fluid pressure caused by the pressure limiting device (22) is canceled by the pressure release device (30), leads to the fluid pressure upstream of the return valve (108) rising above the venting pressure limit value and thus to the return valve (108) being opened.Fluid supply system (100) according to one of claims 12 to 15, characterised bya further drivable conveying device (110) which is arranged along the supply line (104a-104c) and outside the filter module (10) and is configured to convey the fluid to the fluid use system (200).Method for operating a fluid supply system (100), in particular a fluid supply system (100) according to one of Claims 12 to 16, having the steps: - filtering a fluid by means of a filter medium (14), through which the fluid can flow, of a filter module (10) of the fluid supply system (100); and - conveying the fluid through the filter module (10) by means of a drivable conveying device (16) of the fluid supply system (100); wherein the fluid pressure of the fluid discharged from the filter module (10) is limited to an operating pressure limit value by means of a pressure limiting device (22) of the filter module (10) in a continuous operating state of the fluid supply system (100); characterized in that the limitation of the fluid pressure of the fluid discharged from the filter module (10), caused by the pressure limiting device (22), is temporarily canceled by means of a pressure releasing device (30) of the filter module (10) in a venting operating state.Method according to claim 17, characterised in that a return valve (28) of the pressure limiting device (22) is arranged behind a pressure release valve (32) of the pressure release device (30) in a return line (26) of the filter module (10) in the direction of flow of the fluid, wherein the pressure release valve (32) of the pressure release device (30) is actuated in the venting operating state and causes the return valve (28) of the pressure limiting device (22) to close.Method according to Claim 17 or 18, characterized in that, in the steady operating state of the fluid supply system (100), the conveying device (16) produces a conveying capacity which at least temporarily causes a limitation of the fluid pressure of the fluid discharged from the filter module (10) by means of the pressure limiting device (22) to the operating pressure limit value, wherein, in the venting operating state of the fluid supply system (100), the conveying device (16) produces a conveying capacity which, when the limitation of the fluid pressure caused by the pressure limiting device (22) is canceled by the pressure releasing device (30), leads to the fluid pressure upstream of a return valve (108) of the fluid supply system (100) rising above a venting pressure limit value and thus to the open of the return valve (108).

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