Tank with replaceable filter unit, for example for diesel exhaust fluid

Abstract

An assembly (100) includes a tank (10) having a bottom mounted outlet unit (30) and a tubular filter unit (50) mounted and removed independently of the outlet unit (30) via a manhole (12) in the top of the tank. The filter unit (50) has a bottom opening (53) which is sealingly closed by engagement of the filter unit (50) with the tank (10) and outlet unit (30) subassembly (1). The tank (10) may be mounted on a vehicle (101) to supply DEF to a diesel exhaust aftertreatment system (103).

Description

Technical Field

[0001] The present invention relates to a storage tank, particularly for supplying diesel exhaust fluid (referred to herein as DEF) to an exhaust aftertreatment system, and particularly for commercial work vehicles used on off-road work sites. Background Art

[0002] Diesel-powered work vehicles, such as wheeled or tracked excavators, loaders, and other construction vehicles used on off-road work sites, are exposed to dusty conditions that can lead to contamination of the DEF tanks used to supply the exhaust aftertreatment systems. To ensure a clean supply of DEF to the system, it is known to protect the header unit that draws DEF from the tank within a tubular filter.

[0003] For example, US Pat. No. 11,331,605 discloses a DEF tank having a sensor unit comprising a heater and DEF supply and return lines disposed within a replaceable tubular filter. The sensor unit is inserted and removed through a hole in the top of the tank. The filter can be inserted and removed through an opposing hole in the bottom of the tank.

[0004] US11268419 B2 and US9468875 B2 disclose DEF tanks having a header assembly that is disposed within a tubular filter and mounted via holes in the top of the tank.

[0005] In this arrangement, DEF is drawn from an inlet in a sensor unit or manifold unit via a DEF pump mounted on the vehicle chassis. The DEF pump supplies fluid to a DEF injector in the aftertreatment system and typically also returns unused DEF to the tank. Typically, the manifold unit will include a heater extending through the depth of the liquid in the tank, typically carrying the engine coolant flow, and a level sensing arrangement extending alongside the heater. This level sensing arrangement is designed to handle significant sloshing of the DEF in the tank.

[0006] In contrast to off-road vehicles, vehicles designed primarily for use on public roads are typically equipped with a DEF tank featuring an integrated, non-removable pump and filter unit. This DEF tank may also include an electric heater and an immersion-type ultrasonic level sensor for sensing the DEF level in the tank. Under typical operating conditions, which are less demanding than those in off-road operating environments, such a unit is expected to last the life of the vehicle without maintenance. The pump and filter unit are typically permanently affixed to the tank. For example, the tank, the pump body, and the filter unit may all be made of plastic material, and the pump body and filter unit may be welded to the tank wall.

[0007] This integrated assembly reduces manufacturing costs compared to traditional off-road assemblies, but has the disadvantage that in the event the filter becomes clogged, the entire tank, pump and filter unit assembly needs to be replaced. Summary of the Invention

[0008] According to the present invention there is provided an assembly as defined in claim 1. Optional features are defined in the dependent claims.

[0009] The novel assembly includes a tank subassembly and a filter unit.

[0010] The storage tank subassembly includes a storage tank and an outlet unit. The storage tank defines an interior space for containing liquid and has an access hole formed in the upper wall of the storage tank. The outlet unit is mounted on the lower wall of the storage tank and has a liquid inlet and a liquid outlet. The outlet unit is configured to supply liquid from the storage tank via the liquid inlet to the liquid outlet.

[0011] The filter unit has a liquid-permeable tubular wall surrounding an interior space of the filter unit, and is arranged in a use position within the tank such that the interior space of the filter unit occupies a first portion of the interior space of the tank, and the tubular wall forms a barrier between the first portion of the interior space of the tank and a second portion of the interior space of the tank that is external to the filter unit. In the use position of the filter unit, the liquid inlet is arranged in fluid communication with the first portion of the interior space of the tank.

[0012] The filter unit has a bottom opening which is formed at a lower end of the filter unit and communicates with the inner space of the filter unit when considered in its use position.

[0013] The filter unit releasably and sealingly engages the tank subassembly to sealingly close the bottom opening in the filter unit's use position, and the filter unit is installable and removable independently of the outlet unit via the manhole. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Further features and advantages will be appreciated from the illustrative embodiments which will now be described by way of example only and not limiting the scope of the claims, and with reference to the accompanying drawings, in which:

[0015] Figure 1 shows a first assembly according to a first embodiment of the invention, with the tank partially cut away to reveal the filter unit in its use position;

[0016] Figure 2 The storage tank subassembly of the first assembly is shown;

[0017] Figure 3 The filter unit of the first assembly is shown;

[0018] Figure 4 shows a second assembly according to a second embodiment of the invention, with the tank partially cut away to reveal the filter unit in its use position;

[0019] Figure 5 The storage tank subassembly of the second assembly is shown;

[0020] Figure 6 The filter unit of the second assembly is shown; and

[0021] Figure 7 A work vehicle including an assembly according to an embodiment of the invention is shown.

[0022] Reference numerals and characters that appear in more than one drawing indicate identical or corresponding elements in each of them. DETAILED DESCRIPTION

[0023] refer to Figure 1-3 The first assembly 100 includes a storage tank subassembly 1 and a filter unit 50 .

[0024] Specific reference Figure 2 The tank subassembly 1 includes a tank 10 and an outlet unit 30. The tank 10 defines an interior space 11 for containing a liquid 2 and has an access hole 12 formed in an upper wall 13 of the tank 10. The liquid may be diesel exhaust fluid, referred to herein as DEF, for treating diesel exhaust.

[0025] Typically, DEF is a urea-water solution that acts as a reducing agent in the selective catalytic reduction unit of a vehicle's exhaust system. Figure 7 The diagram shows how the assembly 100 can be incorporated into a vehicle 101, which includes a diesel engine 102 and an exhaust aftertreatment system 103 for treating exhaust gas 104 emitted by the engine 102. The outlet unit 30 is configured to supply liquid 2 from the storage tank 10 to the exhaust aftertreatment system 103 of the vehicle, which can be a wheeled or tracked working vehicle for off-road use. For example, it can be a dump truck, an excavator, or a wheel loader, as shown.

[0026] The outlet unit 30 is mounted at the lower wall 14 of the storage tank 10 and has a liquid inlet 31 and a liquid outlet 32. It is configured to supply DEF or other liquid 2 from the storage tank 10 via the liquid inlet 31 to the liquid outlet 32. In the case where the liquid is DEF, the liquid outlet 32 will be connected to a liquid injector or other outlet in the exhaust aftertreatment system 103.

[0027] The outlet unit 30 can be permanently fixed to the storage tank 10, for example by welding or otherwise bonding the body of the outlet unit to the wall of the storage tank. In such an arrangement, the outlet unit can be considered a non-serviceable component, so that in the event of a malfunction, the storage tank and the outlet unit must be replaced together as a single assembly. The storage tank can be made of any material that is suitable for (or has a coating suitable for) DEF or other contained liquids. For example, it can be made of metal or plastic material. In the case where both the storage tank and the body of the outlet unit 30 are made of plastic material, the outlet unit can be welded to the storage tank, for example, by ultrasonic welding.

[0028] As shown in the second assembly, where the tank 10 is formed of a plastic material, the base of the tank may be locally thickened to define a boss 18 integrally formed with the lower wall 14 of the tank, the boss 18 incorporating an engagement feature 15 for engaging the filter unit 50 to mechanically connect the filter unit to the tank subassembly 1, as discussed further below. The boss provides stiffness to react to torque or other forces applied during installation of the filter unit 50.

[0029] As shown in the first and second assemblies, in the in-use position of the filter unit 50, the outlet unit 30 may extend into the interior space 52 of the filter unit 50 via the bottom opening 53. Usefully, this elevates the functional parts of the outlet unit above any debris that may have collected at the base of the tank, and provides a compact assembly that is easier to install because only the outlet 32 (and other electrical and / or fluid connections, not shown) may protrude below the bottom wall of the tank.

[0030] The outlet unit 30 may include a pump 34 and an outlet unit filter 35 and / or a heater 36 for heating the DEF or other liquid 2 in the tank. Such units are commercially available and well known in the art. In such an arrangement, the outlet unit filter 35 is configured to filter the liquid 2 supplied from the tank 10 via the pump 34, which pushes the liquid 2 from the inlet 31 through the filter 35 and the outlet 32 to its point of use, such as an injector in the exhaust aftertreatment system 103. The outlet unit filter 35 may be an integral part of the outlet unit 30; in other words, the filter 35 cannot be removed from the outlet unit without destroying the outlet unit.

[0031] The outlet unit 30 may include an ultrasonic level sensor 33 that is operable to generate an ultrasonic signal to sense the liquid surface level 3 in the tank 10. In the use position of the filter unit 50, the tubular wall 51 extends above a maximum liquid surface level 3' in the tank 10 (this liquid surface level may be defined, for example, by a level gauge or by the position of the filler inlet 37). The level sensor 33 is arranged to sense the liquid surface level 3 within the interior space 52 of the filter unit 50 in its use position. As is known in the art, the level sensor 33 can sense the level of the liquid in the interior space within the filter based on the time of flight of an ultrasonic signal that is emitted from the submerged sensor 33 and then detected again at the sensor 33 after being reflected back from the liquid surface.

[0032] Specific reference Figure 3 , the filter unit 50 has a liquid-permeable tubular wall 51 surrounding the interior space 52 of the filter unit 50. As shown in the figure, the tubular wall 51 can be cylindrical, forming a surface of rotation around the central length axis X. It can include a liquid-permeable filter material or membrane supported by a frame. The filter material can include two or more layers of material that can be connected together. The filter material can have a combination of two or more different structures, for example, to form a pleated cylindrical filter. When in its use position, the filter unit 50 has a bottom opening 53 formed at the lower end 54 of the filter unit 50, which is connected to the interior space 52.

[0033] The filter material is shown as transparent purely for ease of illustration so that we can see the outlet unit 30 inside the filter; it will be appreciated, of course, that the filter material can be as dense as necessary to capture the designed particle size and can therefore be opaque in practice, as is conventional in the art. To accommodate flexing of the tank in use, the filter material can be flexible, allowing the length of the filter unit to adapt to variations in the distance between the upper and lower walls of the tank and / or allowing the tubular wall to flex to accommodate relative movement between the upper and lower ends of the filter unit out of the plane of its longitudinal axis X, thereby accommodating relative displacement between the top and bottom structures of the tank.

[0034] Now specific reference Figure 1 , the filter unit 50 is arranged in the tank 10 in its use position such that the interior space 52 of the filter unit 50 occupies the first part 11 ′ of the interior space 11 of the tank 10 and the tubular wall 51 forms a barrier between the first part 11 ′ of the interior space 11 of the tank 10 and the second part 11 ″ of the interior space 11 of the tank 10 outside the filter unit 50.

[0035] The liquid inlet 31 is arranged in fluid communication with the first part 11 ′ of the interior 11 of the tank 10 , in other words with the interior 52 of the filter unit 50 in its use position, so that liquid is sucked by the pump 34 (if provided) from the second part 11 ″ of the interior through the tubular wall 51 into the interior 52 of the filter unit and then from the interior 52 of the filter unit 50 into the inlet 31.

[0036] In its use position, the filter unit 50 is releasably and sealingly engaged with the tank subassembly 1 to sealingly close the bottom opening 53, in other words, to close the bottom opening so that liquid in the second part 11 ″ of the interior space of the tank outside the filter unit cannot enter the inlet 31 without first passing through the tubular wall 51.

[0037] The engagement surface formed on the filter unit 50 at the bottom opening 53 can engage a corresponding engagement surface of the tank subassembly 1 (e.g., of the tank 10 or the outlet unit 30) to mechanically secure the filter in its use position and / or sealingly close the bottom opening 53. The first and second embodiments illustrate two alternative arrangements of this type with respective engagement features 55, 15, as discussed further below. Alternatively or additionally, one or more seals (not shown) can be provided to seal the bottom opening 53, with the corresponding engagement surfaces achieving the mechanical connection, the one or more seals forming part of either or both of the filter unit 50 and the tank subassembly 1.

[0038] The filter unit 50 is installable and removable independently of the outlet unit 30 via the manhole 12, and can therefore be replaced with a new filter unit simply by detaching it from the tank subassembly 1 and lifting it out of the tank through the manhole 12, without removing or disturbing the outlet unit 30 which may be permanently fixed in the tank as described above.

[0039] Conveniently, the filter unit 50 is releasably sealingly engageable with the tank subassembly 1 by rotation of the filter unit 50 about the longitudinal axis X of the tubular wall 51 to sealingly close the bottom opening 53 .

[0040] Figure 4-6 A second assembly is shown which is generally similar to the first assembly, having the same features as described above, but with some differences, as will now be discussed.

[0041] As shown in the first and second assemblies, the filter unit 50 may include a handle 61 and an upper end wall 62, which are arranged at the upper end 57 of the filter unit 50 opposite the lower end 54. The upper end wall 62 defines the interior space 52 of the filter unit 50, which can be opened only via the bottom opening 53, which is sealed closed in its use position. The handle 61 is graspable to manipulate the filter unit 50 during installation and removal.

[0042] As in the first embodiment ( Figure 1-3 ), the filter unit 50 including the handle 61 can be completely housed within the tank 10 in its use position. In such an arrangement, the manhole 12 can be closed by a separate cover 17 having suitable fixings (not shown).

[0043] As in the second embodiment ( Figure 4-6 ), the filter unit 50 can be exposed at its upper end 57 in its use position, so that the handle is accessible from the outside of the tank 10.

[0044] Now refer to Figure 4-6 In the second embodiment, the filter unit 50 may include a closure plate 60 disposed at an upper end 57 of the filter unit 50 opposite the lower end 54. The closure plate 60 releasably and sealingly engages the tank 10 to sealingly close the access hole 12 in the use position of the filter unit 50.

[0045] In such an arrangement, as shown, the filter unit 50 may include a handle 61 connected to the closure plate 60 and exposed outside the tank 10 in the use position of the filter unit 50. The handle 61 is graspable to manipulate the filter unit 50 during installation and removal.

[0046] The closure plate 60 may be sealingly engageable with the tank 10 to sealingly close the manhole 12 by rotation of the filter unit 50 about the length axis X of the tubular wall 51 .

[0047] The closure plate 60 and the filter unit 50 are simultaneously and sealingly engageable with the storage tank 10 to sealingly close the access hole 12 and with the storage tank subassembly 1 to sealingly close the bottom opening 53 , respectively.

[0048] As shown, by rotating the filter unit 50 about the longitudinal axis X of the tubular wall 51, the closure plate 60 and the filter unit 50 can be simultaneously and sealingly engaged with the tank 10 to sealingly close the access hole 12, and with the tank subassembly 1 to sealingly close the bottom opening 53.

[0049] Now refer to the first and second embodiments ( Figure 1-3and Figure 4-6 ), the lower end 54 of the filter unit 50 may include a first engagement feature 55, wherein the tank subassembly 1 includes a corresponding second engagement feature 15. The first engagement feature 55 and the second engagement feature 15 are configured to engage together to constrain the filter unit 50 to simultaneously translate axially along the longitudinal axis X of the tubular wall 51 and rotate about the longitudinal axis X of the tubular wall 51 toward the use position.

[0050] In a first embodiment, the first engagement feature 55 is formed as one or more guiding surfaces, such as the guiding surfaces of a groove as shown, while the second engagement feature 15 is formed as an engagement surface, such as the engagement surface of a protrusion as shown. A corresponding protrusion (not shown) can be provided in a position radially opposite the illustrated protrusion to engage another corresponding groove (not shown). The protrusion or each protrusion fits into the corresponding groove so that the features 55 and 15 cooperate to form a bayonet connection, wherein the corresponding surfaces slide together to guide the filter unit 50 axially and rotationally. As shown, the bayonet connection can be arranged to provide a slight over-centering effect, thereby locking the filter unit 50 in place when sufficient torque is applied to the handle 61 to cause a slight bending of the filter unit 50 or a resilient O-ring or other seal (not shown). The resilient O-ring or other seal is configured to seal the bottom opening 53, thereby allowing the protrusion to move through the uppermost portion of the groove when the filter unit 50 is fully rotated to the use position.

[0051] As shown, the bottom opening 53 can be sealingly closed by sliding abutment between corresponding radially opposing surfaces at the lower end of the filter unit 50 and the outlet unit 30, or by a separate seal (not shown) which can be compressed by moving the filter unit 50 into its use position.

[0052] In an alternative arrangement, the corresponding bayonet features may be reversed to provide a groove or other guiding surface on the tank subassembly 1 and a protrusion on the filter unit 50 .

[0053] In the second embodiment, the first engagement feature 55 and the second engagement feature 15 are configured as cooperating threads, which extend helically around the central axis X of the filter unit 50. The bottom opening 53 can be sealingly closed by sliding abutment between the corresponding threads, or by sliding abutment between the lower end portion of the filter unit 50 and corresponding diametrically opposed surfaces of the outlet unit 30, which extends inside the lower end of the filter unit 50 in the use position of the filter unit 50, or by a separate seal (not shown) which can be compressed by moving the filter unit 50 into its use position.

[0054] Also as in the second embodiment ( Figure 4-6 ), the closure plate 60 may include a first sealing surface 63, wherein the storage tank 10 includes a second sealing surface 16, and at least one of the first and second sealing surfaces 63, 16 is cylindrical. When considered in the use position of the filter unit 50, each of the first and second sealing surfaces 63, 16 is a surface of revolution about the longitudinal axis X of the tubular wall 51. The first and second sealing surfaces 63, 16 are sealingly engageable together to sealingly close the access hole 12.

[0055] Advantageously, this decouples rotation between the first sealing surface 63 and the second sealing surface 16 from axial movement of the filter unit 50, thereby allowing relative rotation between the sealing surfaces regardless of their relative positions along the longitudinal axis X, making the assembly tolerant to dimensional changes due to, for example, flexure of the tank wall. In the illustrated embodiment, the first sealing surface 63 is formed in an annular groove in the lower surface of the closure plate 60, while the second sealing surface 16 is formed as a cylindrical rim surrounding the manhole 12. In an alternative arrangement (not shown), the respective one of the sealing surfaces may be formed as an O-ring or other resilient seal.

[0056] Industrial Applicability

[0057] The filter unit of the new assembly filters out debris before it reaches the outlet unit, thereby extending the life of the outlet unit, which includes a pump and an integral filter located therein. This makes it possible to use conventional outlet units designed for on-road vehicles in work vehicles intended for off-road use.

[0058] In this novel assembly, the design life of the outlet unit (including its integral filter) can be expected to last for the life of the vehicle, even when used in off-road conditions. This means that the outlet unit does not need to be replaceable and can therefore be permanently fixed to the bottom of the tank, which is generally the optimal location for both functionality and ease of manufacturing. The outlet unit can be permanently bonded, such as welded (e.g., ultrasonically welded), to the tank, which avoids any risk of leakage through defective seals.

[0059] By arranging the filter unit to be removable and replaceable independently of the outlet unit via a seal access hole at the top of the tank, the risk of leakage from the seal is reduced (as it is above the liquid level in the tank) and the filter unit is easier to replace as there is no need to drain the tank or remove the outlet unit.

[0060] When installing a new filter unit, the bottom opening allows liquid already present in the tank to flow into the interior space within the filter unit, while air trapped within the new filter unit (which is less dense than the liquid) quickly escapes through the permeable tubular wall when it is introduced into the tank. This makes it possible to quickly and easily install a new filter unit when the tank is full of liquid without causing liquid to overflow from the tank, even in cases where the filter unit is relatively large and therefore has an advantageously large surface area for better filtration performance.

[0061] A bayonet or threaded connection at the lower end of the filter unit may provide a secure connection while allowing the filter unit to be replaced with minimal effort, even without tools by means of a graspable handle.

[0062] Maintenance is further simplified by an integral outlet plate that closes the maintenance hole without additional components. By arranging the outlet plate to seal the maintenance opening via a cylindrical sealing surface (unlike the lower end connection, which does not axially constrain the filter unit), the bottom opening and the maintenance hole can be sealingly closed simultaneously, while providing tolerance to accommodate changes in the distance between the upper and lower walls of the tank as the tank flexes.

[0063] By arranging the outlet unit to extend within the first filter unit during use, all functional wetted parts of the outlet unit are protected by the filter unit. This also ensures that the inlet is positioned within the interior space of the first filter unit, even when the inlet is formed as a simple hole in the body of the outlet unit. This allows the first filter unit to be used in tanks with conventionally designed outlet units, avoiding the need to adjust the inlet position.

[0064] Advantageously, where the outlet unit includes an ultrasonic level sensor, the filter extends above the maximum level of the liquid in the tank, thereby not interfering with the operation of the level sensor. Further advantageously, the filter suppresses sloshing of the liquid within the tank and also suppresses foaming of the liquid by breaking up any larger bubbles that may form. This provides a relatively more constant ultrasonic level signal by sensing a relatively more constant level of the liquid in the interior space within the filter, enabling ultrasonic level sensing to be used in place of other level sensing arrangements typically used in off-road vehicles, where expected off-road field conditions may cause significant agitation of the tank during use.

[0065] The novel assembly can be used with fluids other than DEF or DEF. In either case, the tank can be mounted on a vehicle, particularly a work vehicle for off-road use.

[0066] In summary, the assembly includes a tank with a bottom-mounted outlet unit and a tubular filter unit that can be installed and removed independently of the outlet unit via a manhole in the tank top. The filter unit has a bottom opening that is sealingly closed by the engagement of the filter unit with the tank and outlet unit subassembly. The tank can be mounted on a vehicle to supply DEF to a diesel exhaust aftertreatment system.

[0067] Many further adaptations are possible within the scope of the claims.

[0068] In the claims, reference numerals and characters provided in parentheses are purely for convenience of reference and shall not be construed as limiting features.

Claims

1. An assembly (100), comprising: a storage tank subassembly (1), and filter unit (50); The storage tank subassembly (1) comprises a storage tank (10) and an outlet unit (30); The storage tank (10) defines an inner space (11) for containing the liquid (2) and has an inspection hole (12) formed in an upper wall (13) of the storage tank (10); The outlet unit (30) is installed at the lower wall (14) of the storage tank (10) and has a liquid inlet (31) and a liquid outlet (32), and is configured to supply the liquid (2) from the storage tank (10) to the liquid outlet (32) via the liquid inlet (31); The filter unit (50) has a liquid-permeable tubular wall (51) surrounding an interior space (52) of the filter unit (50); The filter unit (50) is arranged in a use position within the tank (10) such that the interior space (52) of the filter unit (50) occupies a first portion (11') of the interior space (11) of the tank (10), and the tubular wall (51) forms a barrier between the first portion (11') of the interior space (11) of the tank (10) and a second portion (11") of the interior space (11) of the tank (10) outside the filter unit (50); In the use position of the filter unit (50), the liquid inlet (31) is arranged in fluid communication with the first portion (11') of the interior space (11) of the tank (10); The filter unit (50) has a bottom opening (53) formed at a lower end (54) of the filter unit (50) and communicating with the inner space (52) of the filter unit (50) when considered in its use position; The filter unit (50) is releasably and sealingly engaged with the tank subassembly (1) to sealingly close the bottom opening (53) in the use position of the filter unit (50); The filter unit (50) is installable and removable independently of the outlet unit (30) via the manhole (12).

2. An assembly (100) according to claim 1, wherein the outlet unit (30) includes a liquid level sensor (33) that is operable to generate an ultrasonic signal to sense the liquid surface level (3) in the tank (10); and the tubular wall (51) extends above a maximum liquid surface level (3') in the tank (10), wherein the liquid level sensor (33) is arranged to sense the liquid surface level (3) within the interior space (52) of the filter unit (50).

3. An assembly (100) according to claim 1, wherein the filter unit (50) is releasably and sealingly engageable with the tank subassembly (1) by rotation of the filter unit (50) about the longitudinal axis (X) of the tubular wall (51) to sealingly close the bottom opening (53).

4. An assembly (100) according to claim 1, wherein the filter unit (50) includes a handle (61) and an upper end wall (62), and the handle (61) and the upper end wall (62) are arranged at an upper end (57) of the filter unit (50) opposite to the lower end (54); the upper end wall (62) defines the interior space (52) of the filter unit (50); the handle (61) is graspable to manipulate the filter unit (50) during installation and removal.

5. An assembly (100) according to claim 1, wherein the filter unit (50) includes a closing plate (60) which is arranged at an upper end (57) of the filter unit (50) opposite to the lower end (54); the closing plate (60) is releasably and sealingly engaged with the tank (10) to sealingly close the inspection hole (12) in the use position of the filter unit (50).

6. An assembly (100) according to claim 5, wherein the filter unit (50) includes a handle (61) connected to the closing plate (60), the handle (61) being exposed to the outside of the tank (10) in the use position of the filter unit (50) and being graspable to manipulate the filter unit (50) during installation and removal.

7. An assembly (100) according to claim 5, wherein the closing plate (60) is sealingly engageable with the tank (10) to sealingly close the inspection hole (12) by rotation of the filter unit (50) about the longitudinal axis (X) of the tubular wall (51).

8. The assembly (100) of claim 5, wherein the closure plate (60) and the filter unit (50) are simultaneously and sealingly engageable with the tank (10) to sealingly close the manhole (12) and with the tank subassembly (1) to sealingly close the bottom opening (53).

9. An assembly (100) according to claim 5, wherein the closure plate (60) and the filter unit (50) are simultaneously and sealingly engageable with the tank (10) to sealably close the inspection hole (12) and are engageable with the tank subassembly (1) to sealably close the bottom opening (53) by rotating the filter unit (50) around the longitudinal axis (X) of the tubular wall (51).

10. An assembly (100) according to claim 9, wherein the lower end (54) of the filter unit (50) includes a first engagement feature (55) and the tank subassembly (1) includes a second engagement feature (15), the first engagement feature (55) and the second engagement feature (15) being configured to engage together to constrain the filter unit (50) to simultaneously translate axially along the length axis (X) of the tubular wall (51) and to move rotationally about the length axis (X) of the tubular wall (51) toward the use position.

11. An assembly (100) according to claim 10, wherein the closing plate (60) includes a first sealing surface (63) and the tank (10) includes a second sealing surface (16); at least one of the first sealing surface (63) and the second sealing surface (16) is cylindrical; when considered in the use position of the filter unit (50), the first sealing surface (63) and the second sealing surface (16) are each a surface of rotation around the length axis (X) of the tubular wall (51); the first sealing surface (63) and the second sealing surface (16) are sealingly engageable together to sealingly close the inspection hole (12).

12. The assembly (100) according to claim 1, wherein in the use position of the filter unit (50), the outlet unit (30) extends via the bottom opening (53) into the inner space (52) of the filter unit (50).

13. The assembly (100) of claim 1, wherein the outlet unit (30) is permanently fixed to the tank (10).

14. The assembly (100) of claim 1, wherein the outlet unit (30) comprises a pump (34) and an outlet unit filter (35), the outlet unit filter (35) being configured to filter the liquid (2) supplied from the storage tank (10) via the pump (34).

15. The assembly (100) of claim 1, wherein the tubular wall (51) is cylindrical.

16. A vehicle (101) comprising a diesel engine (102), an exhaust gas aftertreatment system (103) for treating exhaust gas (104) emitted by the engine (102), and an assembly (100) according to any one of the preceding claims, wherein the outlet unit (30) is configured to supply the liquid (2) from the tank (10) to the exhaust gas aftertreatment system (103).

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