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Title:
FILTER UNIT
Document Type and Number:
WIPO Patent Application WO/2015/169327
Kind Code:
A1
Abstract:
The invention concerns a filter unit (10, 20, 30, 40) for an internal combustion engine (1), wherein the filter unit (10, 20, 30, 40) comprises a filter housing (12) and means (14, 15) for transfer of a fluid between the filter unit (10, 20, 30, 40) and the engine (1) at a first end (16) of the filter housing (12) The invention is characterized in that the filter unit (10, 20, 30, 40) comprises a cylindrical wall (11, 21, 23, 31, 41) that is connected to the filter housing (12), that the cylindrical wall (11, 21, 23, 31, 41) is configured for collecting leakage fluid when disconnecting the filter unit (10, 20, 30, 40) from the engine (1), and that the cylindrical wall (11, 21, 23, 31, 41) is configured to be arranged in at least two different states in relation to the filter housing (12) comprising an inactive state, when the filter unit (10, 20, 30, 40) is in its filtering operational position and an active state, in which it projects a distance from the first end (16) of the filter housing (12) for collecting leakage fluid when disconnecting the filter unit (10, 20, 30, 40) from the engine (1). The invention also concerns an internal combustion engine (1) comprising a filter unit (10, 20, 30, 40) of the above type.

Inventors:
LARSSON CHRISTIAN (SE)
OMERSPAHIC ERVIN (SE)
FRENNFELT CLAES (SE)
ANDERSSON ARNE (SE)
BODÉN ROGER (SE)
Application Number:
PCT/EP2014/001243
Publication Date:
November 12, 2015
Filing Date:
May 08, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
VOLVO TRUCK CORP (SE)
International Classes:
B01D35/16; B01D35/31
Domestic Patent References:
WO2011041018A22011-04-07
Foreign References:
US20040226878A12004-11-18
US4376703A1983-03-15
US4451368A1984-05-29
US4865727A1989-09-12
US5366084A1994-11-22
Other References:
None
Attorney, Agent or Firm:
JÖNRUP Emil (Volvo Corporate Intellectual PropertyDept: BF1410, M1.7 Göteborg, SE)
Download PDF:
Claims:
CLAIMS

1. A filter unit (10, 20, 30, 40) for an internal combustion engine (1), wherein the filter unit (10, 20, 30, 40) comprises a filter housing (12) and means (14, 15) for transfer of a fluid between the filter unit (10, 20, 30, 40) and the engine (1) at a first end (16) of the filter housing (12),

characterized in

- that the filter unit (10, 20, 30, 40) comprises a cylindrical wall (11 , 21 , 23, 31 , 41) that is connected to the filter housing (12), that the cylindrical wall (11 , 21 , 23, 31 , 41) is configured for collecting leakage fluid when disconnecting the filter unit (10, 20, 30, 40) from the engine (1), and that the cylindrical wall (11 , 21 , 23, 31 , 41) is configured to be arranged in at least two different states in relation to the filter housing (12) comprising an inactive state, when the filter unit (10, 20, 30, 40) is in its filtering operational position and an active state, in which it projects a distance from the first end (16) of the filter housing (12) for collecting leakage fluid when disconnecting the filter unit (10, 20, 30, 40) from the engine (1).

2. A filter unit (10, 20, 30, 40) according to claim 1 , wherein the filter unit (10, 20, 30, 40) has a longitudinal axis extending between the first end (16) and a second, opposite end (13) of the filter housing (12), wherein the cylindrical wall (11 , 21 , 23, 31 , 41) is extendable or movable in a direction along the longitudinal axis so as to be extended or moved into its active state.

3. A filter unit (10, 20, 30, 40) according to claim 1 or 2, wherein the cylindrical wall (11 , 21 , 23, 31 , 41), at least when arranged in its inactive state, surrounds the filter housing (12).

4. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the filter unit (10, 20, 30, 40) is configured to be mounted to the engine (1) with its first end (16) facing in an upwards direction, wherein the cylindrical wall (11 , 21 , 23, 31 , 41) is configured to, when arranged in its active state, form an oil leakage reservoir above the first end (16) when disconnecting the filter unit (10, 20, 30, 40) from the engine (1).

5. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the filter unit (10, 20, 30, 40) comprises a resilient arrangement (11 , 23, 33) configured to set the cylindrical wall (11 , 21 , 23, 31, 41) in its active state when the filter unit (10, 20, 30, 40) is disconnected from the engine (1).

6. A filter unit (10, 20, 30, 40) according to claim 5, wherein the resilient arrangement (11 , 23, 33) is configured to be set in a stressed state when the cylindrical wall (11 , 21 , 23, 31 , 41) is arranged in its inactive state.

7. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein at least a part of the cylindrical wall (11 , 21 , 23, 31 , 41) is formed of a movable sleeve (21 , 31 , 41).

8. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein at least a part of the cylindrical wall (11 , 21 , 23, 31 , 41) is formed of an extendable wall structure (11 , 23).

9. A filter unit (10, 20, 30, 40) according to claim 8, wherein the extendable wall structure (11 , 23) is a corrugated wall structure.

10. A filter unit (10, 20, 30, 40) according to claim 8, wherein the extendable wall structure (11 , 23) is a telescopic structure comprising a plurality of concentrically arranged annular wall sections connected by annular connection members.

11. A filter unit (10, 20, 30, 40) according to claim 5 and 9, wherein the corrugated wall structure (11 , 23) exhibits resilient properties and forms at least part of the resilient arrangement (11 , 23, 33).

12. A filter unit (10, 20, 30, 40) according to claim 5 and 10, wherein the annular connection members exhibit resilient properties and forms at least part of the resilient arrangement (11 , 23, 33). 13. A filter unit (10, 20, 30, 40) according to claim 5 or 6, wherein the resilient arrangement (11 , 23, 33) comprises one or several resilient elements (33) that are configured to act onto the cylindrical wall (11 , 21 , 23, 31 , 41).

14. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the cylindrical wall (11 , 21 , 23, 31 , 41) is provided with an attachment means (46, 47) configured to be attached to the engine (1) so as to hold the filter unit (10, 20, 30, 40) in place when the filter unit (10, 20, 30, 40) is disconnected from the engine (1). 15. A filter unit (10, 20, 30, 40) according to claim 14, wherein the attachment means (46, 47) comprises a radially protruding element.

16. A filter unit (10, 20, 30, 40) according to claim 14 or 15, wherein the attachment means (46, 47) is rotationally asymmetric.

17. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the cylindrical wall (11 , 21 , 23, 31 , 41 ) surrounds the fluid transfer means (14, 15). 18. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the cylindrical wall (11 , 21 , 23, 31 , 41) is sealed to the filter housing (12).

19. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the cylindrical wall (11 , 21 , 23, 31 , 41), when arranged in its active state and projecting a distance from the first end (16) of the filter housing (12), defines an oil collecting volume in the range 0.2 - 0.8 L, preferably around 0.5 L, at the first end (16) of the filter housing (12).

20. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the filter housing (12) encloses a filter chamber and wherein the first end (16) is provided with at least one inlet opening (14) and at least one outlet opening (15) for leading fluid to and from the filter chamber.

21. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the filter housing (12) comprises a second, opposite end (13), which forms a closed end.

22. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the fluid transfer means is formed by a set of openings (14, 15) in the first end (16). 23. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the filter unit (10, 20, 30, 40) comprises means for connecting the filter unit (10, 20, 30, 40) to the internal combustion engine (1).

24. A filter unit (10, 20, 30, 40) according to claim 23, wherein the connecting means is positioned at the first end (16).

25. A filter unit (10, 20, 30, 40) according to claim 23 or 24, wherein the connecting means is formed by a threaded opening (15) in the first end (16). 26. A filter unit (10, 20, 30, 40) according to any of the above claims, wherein the filter unit (10, 20, 30, 40) is configured for filtering an engine oil.

27. Internal combustion engine (1),

characterized in

that it comprises a filter unit (10, 20, 30, 40) according to any of the above claims.

Description:
Filter unit

TECHNICAL FIELD

This invention relates to a filter unit for an internal combustion engine, wherein the filter unit comprises a filter housing and means for transfer of a fluid between the filter unit and the engine at a first end of the filter housing.

The invention also relates to an internal combustion engine provided with such a filter unit.

BACKGROUND OF THE INVENTION

A common type of oil filters for internal combustion engines, a so-called spin- on filter design, consists of a housing/canister with a filter element placed inside. The housing has oil inlet and outlet arranged so that oil that flows from inlet to outlet is forced to pass through the filter element. Typically, the inlet and outlet are placed together with each other in one end of the housing with a central outlet/inlet surrounded by a number of smaller inlets/outlets. In such a case the filter element normally has the general shape of a hollow cylinder through which the oil flows in a radial direction. The housing is mounted either directly on the engine or remotely with supply and return pipes connecting it to the engine. When changing such an oil filter, the housing is unscrewed from its mount, discarded, and replaced with a new one.

Removal of a used oil filter of the above type normally leads to spilling and dripping of oil as the housing is full of oil. Even if the filter is mounted vertically with its openings, i.e. inlet and outlet, placed on its upper side it is difficult to avoid that oil flows out from the openings and soil the clothing of the mechanic and/or the floor of the garage/workshop. There is thus a need for improvements in the field of reducing or eliminating spilling and dripping of oil when changing/removing oil filters of the above type. SUMMARY OF THE INVENTION

The invention concerns a filter unit for an internal combustion engine, wherein the filter unit comprises a filter housing and means for transfer of a fluid between the filter unit and the engine at a first end of the filter housing.

The invention is characterized in that the filter unit comprises a cylindrical wall that is connected to the filter housing, that the cylindrical wall is configured for collecting leakage fluid when disconnecting the filter unit from the engine, and that the cylindrical wall is configured to be arranged in at least two different states in relation to the filter housing comprising an inactive state, when the filter unit is in its filtering operational position and an active state, in which it projects a distance from the first end of the filter housing for collecting leakage fluid when disconnecting the filter unit from the engine.

When such a filter unit is to be removed and exchanged, the cylindrical wall is set in its active state so that oil that leaks out from the engine or the housing collects and stays in the reservoir inside the wall at the first end of the filter unit, at least in the common and intended situation where the filter unit is arranged more or less in an upright position with the first end facing upwards. This prevents spilling and dripping of oil, and by sealing the wall to the filter housing in a suitable way it also keeps the outside of the housing free from oil.

Further, because an appropriate leakage oil collector is already mounted to the filter housing when the filter unit is to be replaced, no time needs to be spent on adapting and mounting any separate collector or other type of oil- spill preventing device onto the housing before disconnection of the filter unit. This makes the process of changing filter unit not only clean but also quick. In an embodiment of the invention the filter unit has a longitudinal axis extending between the first end and a second, opposite end of the filter housing, wherein the cylindrical wall is extendable or movable in a direction along the longitudinal axis so as to be extended or moved into its active state.

This is a suitable way of bringing about the inactive and active states of the wall, i.e. by extending or moving the wall between the two states. Preferably, the cylindrical wall, at least when arranged in its inactive state, surrounds the filter housing.

In an embodiment of the invention the filter unit is configured to be mounted to the engine with its first end facing in an upwards direction, wherein the cylindrical wall is configured to, when arranged in its active state, form an oil leakage reservoir above the first end when disconnecting the filter unit from the engine.

In an embodiment of the invention the filter unit comprises a resilient arrangement configured to set the cylindrical wall in its active state when the filter unit is disconnected from the engine. Thus, the wall will automatically extend or move into its active state so as to project a distance from the first end of the filter housing. This way the mechanic does not have to take any particular measure to form the fluid or oil reservoir which makes the work simple.

In an embodiment of the invention the resilient arrangement is configured to be set in a stressed state when the cylindrical wall is arranged in its inactive state. This means that by connecting the filter unit to the engine with the cylindrical wall set in its inactive state, the wall will be set in a stressed state that enables an automatic transition to the active state when the filter unit is disconnected from the engine. This allows the cylindrical wall to be set in a stressed, inactive state by pressing it against (a part of) the engine during installation of the filter unit.

In an embodiment of the invention at least a part of the cylindrical wall is formed of a movable sleeve. As an alternative or complement, at least a part of the cylindrical wall is formed of an extendable wall structure. Such an extendable wall structure could be a corrugated wall structure and/or a telescopic wall structure. Preferably, the latter structure comprises a plurality of concentrically arranged annular wall sections connected by annular connection members. Each connection member can connect a first cylindrical wall section (sleeve) to the filter housing or to an adjacent concentrically arranged second wall section.

In an embodiment of the invention the corrugated wall structure exhibits resilient properties and forms at least part of the resilient arrangement.

In an embodiment of the invention the annular connection members exhibit resilient properties and forms at least part of the resilient arrangement. In an embodiment of the invention the resilient arrangement comprises one or several resilient elements that are configured to act onto the cylindrical wall. Such resilient elements are typically separate from the cylindrical wall but are arranged to move or extend the wall so as to arrange the wall in its active state.

As an example, a plurality of spring elements can be circumferentially distributed between a flange on the filter housing and a first, lower edge of the cylindrical wall/sleeve so as to be set in a compressed, stressed when the wall/sleeve is arranged in its inactive state (i.e. when the wall/sleeve is moved towards the flange) and so as to expand and move the wall/sleeve towards and beyond the first end of the filter housing when the filter unit is disconnected from the engine. As an alternative to a plurality of circumferentially distributed resilient elements it is possible to use e.g. a coil spring that surrounds the circumference of a cylindrical filter housing and that is capable of arranging (moving) the cylindrical wall into its active state. Various combinations of separate resilient coils and other resilient elements are possible. Separate resilient elements can also be combined with a cylindrical wall that in itself is extendable and/or resilient. In an embodiment of the invention the cylindrical wall is provided with an attachment means configured to be attached to the engine so as to hold the filter unit in place when the filter unit is disconnected from the engine.

This way the filter unit can be left hanging at the engine to allow oil to run down into the reservoir before detaching the wall and removing the filter unit from the engine. While the filter unit is disconnected but attached and hanging, the mechanic can do other things than simply holding the filter and waiting for the oil to run, such as disconnecting further filter units of the engine. The process of changing filter units can thus be made more effective. Preferably, the wall is configured to be attached to a mating structure arranged onto the engine.

Whereas the operative connection between the filter unit and the engine must be capable of handling a high internal oil pressure, the above mentioned attachment between the cylindrical wall and the engine must only be capable of holding the disconnected filter unit in place at the engine.

In an embodiment of the invention the attachment means comprises a radially protruding element. Such an element, for instance an edge or flange, is suitable for cooperating with a mating structure arranged onto the engine. For instance, if the edge or flange of the wall is flexible it can be snapped into a mating structure that has a slightly differing diameter. Preferably, the edge or flange is arranged at or close to an (upper) end of the circular wall. The protruding element may protrude radially outwards or inwards.

In an embodiment of the invention the attachment means is rotationally asymmetric. This means for instance that the wall can have an edge or flange that is rotationally asymmetric, e.g. one or several flanges that extend only over a portion of the circumference of the wall, or that the wall can be provided with threads. Due to its rotational asymmetry, the wall can be attached to the engine by turning the wall and engage it with a suitable mating structure.

When attaching the wall by turning it is an advantage if the wall is not rotationally fixed to the filter housing but freely rotatable so as to avoid that the entire filter unit needs to be rotated when attaching (or detaching) the circular wall to (from) the engine. If the wall is freely rotatable it allows the wall to be turned and attached before disconnecting the filter unit from the engine (or even before connecting the filter unit to the engine) in the common situation where also the filter unit is connected to the engine by turning (threads). However, a wall that is rotationally fixed to the filter housing can also be used as it is also possible to disconnect the filter unit in a first step and then attach only the wall (arranged in its active state) to the engine by turning it into place.

In an embodiment of the invention the cylindrical wall surrounds the fluid transfer means. Preferably, the cylindrical wall is sealed to the filter housing.

In an embodiment of the invention the cylindrical wall, when arranged in its active state and projecting a distance from the first end of the filter housing, defines an oil collecting volume in the range 0.2 - 0.8 L, preferably around 0.5 L, at the first end of the filter housing. Such a volume is sufficient in most applications but is still not unnecessarily large. The invention is primarily intended for a type of filter unit that comprises one or several of the following features:

- the filter housing encloses a filter chamber and the first end is provided with at least one inlet opening and at least one outlet opening for leading fluid to and from the filter chamber,

- the filter housing comprises a second, opposite end, which forms a closed end,

- the filter unit comprises means for connecting the filter unit to the internal combustion engine,

- the connecting means is positioned at the first end,

- the connecting means is formed by a threaded opening in the first end,

- the filter unit is configured for filtering an engine oil.

BRIEF DESCRIPTION OF DRAWINGS

In the description of the invention given below reference is made to the following figure, in which:

Figure 1 shows an internal combustion engine provided with three filter units according to a first embodiment of the invention, Figure 2 shows the three filter units of figure 1 in a more detailed view, where one of the filter units has been disconnected from the engine,

Figures 3a and 3b show the function of a filter unit according to figure 1 , Figures 4a-4c show the structure and function of a second embodiment of the inventive filter unit,

Figures 5a and 5b show the structure and function of a third embodiment of the inventive filter unit, and

Figures 6a-6c show the structure and function of a fourth embodiment of the inventive filter unit. DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Figure 1 shows an internal combustion engine 1 provided with, in this example, three identical oil filter units 10 (10a, 10b, 10c) according to a first embodiment of the invention. The filter units 10 are positioned vertically side by side and are connected to the engine 1 via their upper side, which in figure 1 is hidden behind a flange 2. Figure 2 shows the three filter units 10a, 10b, 10c of figure 1 in a more detailed view and with the flange 2 removed. The filter unit to the right, filter unit 10c, has been disconnected from a part 3 of the engine 1 in a downwards direction indicated by arrow 9. Figures 3a and 3b show the inventive function of one of the filter units 10 of figure 1.

Each filter unit 10a, 10b, 10c comprises a cylindrical filter housing 12 having a first, upper end 16 (see figures 3a and 3b) and a second, opposite end 13, which forms a closed end. The filter housing 12 has a circular-cylindrical shape. Further, the filter housing 12 is a rigid structure. More specifically, the filter housing 12 comprises a cylindrical wall enclosing a filter chamber. The first and second ends 13,16 are formed by base walls, which delimit the filter chamber along a filter housing centre axis. The base walls are principally in parallel with each other, but may have a somewhat rounded shape.

A set of openings 14, 15 in the first end 16 of the filter housing 12 form means for transfer of a fluid, in this case engine oil, between the filter unit 10 and the engine 1. These openings include a centrally positioned outlet opening 15 and a plurality of smaller inlet openings 14 distributed around the outlet opening 15. The outlet opening 15 is threaded so as to form a connection means for connection to the engine 1.

Figure 2 shows that a pipe-shaped connector 4 on the engine 1 is provided with threads for connection with the threaded outlet opening 15. The connector 4 also forms an oil inlet to the engine 1. The engine part 3 is further provided with oil outlets 5 provided around the connector 4. A rubber seal 17 (see figure 3a) provides for sealing against the engine part 3 when the filter unit 10 is operatively connected to the engine 1. Each filter housing 12 encloses a filter chamber and the filter unit 10 is conventionally arranged in such a way that oil that enters via the inlets 14 is forced towards the filter chamber where it passes through the filter before it returns to the engine 1 via the outlet 15. Each filter unit 10 further comprises a cylindrical wall 11 in the form of a corrugated wall structure that surrounds the filter housing 12 and that is connected to an outside of the filter housing 12 by a sealing glue joint at a lower part 11 ' of the wall 11 (see figures 3a and 3b). The cylindrical wall 11 is in this example resilient and extendable and is configured for collecting leakage oil when disconnecting the filter unit 10 from the engine 1.

The cylindrical wall 11 is configured to be arranged in two different states in relation to the filter housing 12 comprising an inactive, compressed state, when the filter unit 10 is in its filtering operational position (see filter units 10a and 10b in figure 2 and filter unit 10 in figure 3a) and an active state, in which the wall 11 projects a distance from the first end 16 of the filter housing 12 for collecting leakage oil when disconnecting the filter unit 10 from the engine 1 (see filter unit 10c in figure 2 and filter unit 10 in figure 3b). The filter unit 10 has a longitudinal axis extending between the first end 16 and the second, opposite end 13 of the filter housing 12, and the cylindrical wall 11 is in this case extendable in a direction along the longitudinal axis so as to be extended into its active state and thereby form an oil leakage reservoir above the first end 16 when disconnecting the filter unit 10 from the engine ! The cylindrical wall 11 is resilient and will be compressed and set in its stressed, inactive state when connecting the filter unit 10 to the engine. When the filter unit 10 is disconnected from the engine 1 and moved downwards away from the engine part 3, the wall 11 will automatically extend and project a distance from the first end 16 of the filter housing 12 so as to form the oil leakage reservoir above the first end 16.

Figures 4a and 4b show the structure and function of a second embodiment of an inventive filter unit 20. Figure 4c shows a perspective view of the filter unit 20 of figures 4a-4b.

The filter unit 20 shown in figures 4a-4c differs from the filter unit 10 shown in figures 2-3 only in the design of the cylindrical wall so the filter housing 12, the first end 16, the openings 14, 15, etc., are similar.

In the example shown in figures 4a-4c, the cylindrical wall comprises a moveable substantially rigid sleeve 21 connected to a corrugated, resilient wall structure 23 of a type similar to what has been described above. A sealing and guiding ring 22 is arranged on an inside of the sleeve 21 and extends circumferentially around the outside of the filter housing 12. The corrugated wall structure 23 is at a first, upper end fixed to a lower edge of the sleeve 21 and at a second, lower end to the filter housing 12 along the circumference thereof. Both fixations are accomplished by means of an adhesive that provides for a sealed fixation.

When the filter unit 20 is pressed against the engine part 3 and threaded onto the connector 4 (see figure 2), the sleeve 21 is pressed and moved downwards towards the wall structure 23 that becomes compressed, see figure 4a.

When the filter unit 20 is disconnected from the engine 1 , the resilient and compressed wall structure 23 extends and moves the sleeve 21 towards and beyond the first end 16 of the filter housing 12, as indicated by arrows 29 in figure 4a and shown in figure 4b, so that the sleeve 21 projects a distance from the first end 16 and forms in this active state a reservoir above the first end 16 for collecting leakage oil. As shown in figure 4b, the ring 22 is still positioned on an outside of the filter housing 12.

In this example the cylindrical wall includes both the rigid sleeve 21 , that forms the oil reservoir above the first end 16 when the wall is arranged in its active state, and the resilient corrugated wall structure 23, that automatically extends when the filter unit 20 is disconnected and sets the wall in its active state by pushing and moving the sleeve 21 into position.

An advantage of the filter unit 20 shown in figures 4a-4c compared to the example shown in figures 2-3 is that the sleeve 21 is more steady and thereby less likely to get jammed or stuck when connecting the filter unit.

Figures 5a and 5b show the structure and function of a third embodiment of the inventive filter unit 30. The filter unit 30 shown in figures 5a-5b differs from the filter unit 10 shown in figures 2-3 primarily in the design of the cylindrical wall so the filter housing 12, the first end 16, the openings 14, 15, etc., are similar. However, the filter housing 12 is in this case provided with a circumferentially extending flange 34 and a plurality of circumferentially distributed protrusions 35 arranged relatively close to the flange 34 on a side thereof facing the first end 16 of the filter housing 12.

In this example the cylindrical wall is formed of a substantially rigid sleeve 31 arranged around the filter housing 12 between the flange 34 and the first end 16. A sealing and guiding ring 32 is arranged on an inside of the sleeve 31 and extends circumferentially around the outside of the filter housing 12. Each protrusion 35 is provided with a resilient element 33 that is configured to be compressed between the flange 34 and a lower edge of the sleeve 31 and thus set in stressed state when the sleeve 31 is pressed towards the flange 34, i.e. when the wall/sleeve is arranged in its inactive state. This state is shown in figure 5a. This is how it looks when the filter unit 30 has been pressed against the engine part 3 and been connected to the engine 1.

When the filter unit 30 is disconnected from the engine 1 and thus is removed from the engine part 3, the resilient elements 33 expands and pushes/moves the sleeve 31 towards and beyond the first end 16 of the filter housing 12, as indicated by arrow 39 in figure 5a and shown in figure 5b, so that the sleeve 31 projects a distance from the first end 16 and forms in this active state a reservoir above the first end 16 for collecting leakage oil. As shown in figure 5b, the ring 32 is still positioned on an outside of the filter housing 12.

Figures 6a to 6c show the structure and function of a fourth embodiment of the inventive filter unit 40.

The filter unit 40 shown in figures 6a-6c differs from the filter unit 10 shown in figures 2-3 primarily in the design of the cylindrical wall so the filter housing 12, the first end 16, the openings 14, 15, etc., are similar. However, the filter housing 12 is in this case provided with a circumferentially extending flange 43 and sealing structure 42 at the first end 16 thereof. The flange 43 and sealing structure 42 protrude radially outwards and prevent the cylindrical wall, in the form of a movable sleeve 41 , from coming loose from the filter housing 12 when the wall/sleeve 41 is attached to the engine 1 after disconnection of the filter unit 40.

The filter housing 12 is in this example also provided with a lower sleeve stopping flange (not shown) extending circumferentially around the filter housing 12 and protruding radially outwards. This lower flange acts onto a lower edge or flange 44 of the sleeve 41 and prevents the sleeve/wall 41 from falling off the filter housing 12 when the filter unit 40 is held or connected in an upright position. This lower flange thus holds the sleeve 41 in place when it is in its lowest position. The position of this further flange in relation to the axial extension of the filter housing 12 can be adapted to the particular application; it may be placed close to the second end 13 of the filter housing 12 or closer td the first end 16.

In this example the cylindrical wall includes only the substantially rigid movable sleeve 41 which is arranged around the filter housing 12 in a similar way as described in relation to figures 4-5. The sealing structure 42 comprises a sealing and guiding ring arranged to seal and guide against an inside of the sleeve 41 as it is moved along the filter housing in an axial direction thereof.

The cylindrical sleeve/wall 41 is provided with first and second attachment means in the form of first and second radially protruding elements 46, 47 arranged circumferentially spaced and in this design opposite to each other at an upper edge of the sleeve 41. These attachment means 46, 47 are configured to be attached to a mating structure 50 (see figure 6c) of the engine 1 so as to hold the filter unit 40 in place at, but somewhat lower than, its position of connection when the filter unit 40 is disconnected from the engine 1.

The cylindrical sleeve/wall 41 is further provided with an inwardly directed flange 44 (see figure 6b) at its lower edge, i.e. the edge facing the second end 13 of the filter housing 12, which flange 44 has a smaller diameter than the flange 43 and sealing structure 42 arranged at the first end 16 of the filter housing 12 so as to keep the filter housing 12 hanging in place when the filter unit 40 has been disconnected from the engine 1 and the attachment means 46, 47 of the sleeve/wall 41 have been attached to the mating structure 50 of the engine 1. The flange 44 also guides the movement of the sleeve 41 and acts against the further, lower flange of the filter housing 12 to prevent that the sleeve 41 falls off. Figure 6a shows the filter unit 40 with the cylindrical wall/sleeve 41 arranged in an inactive state where it is flush with the first end 16 of the filter housing 12. The filter unit 40 may be arranged so that the sleeve can be positioned closer to the second end 13 to be out of the way when connecting the filter unit 40 to the engine 1. Arrows 48 indicate that the sleeve 41 can be moved (further) axially upwards towards and partly beyond the first end 16 of the filter housing 12 so as to be arranged in its active state where the wall/sleeve 41 projects a distance from the first end 16 and forms a leakage oil reservoir above the first end 16 (see figure 6b). Arrows 49 indicate that the sleeve 41 is freely rotatable in relation to the filter housing 12, which is useful for attaching the attachment means 46, 47 by turning them into place in the mating structure 50 of the engine 1.

Figure 6c shows a view similar to that of figure 2. In figure 6c a first filter unit 40a has been connected to the engine part 3 by threading the outlet opening 15 onto the connector 4 in a way similar to what has been described above. When the filter unit 40a has been connected, the sleeve 41 can be moved/slided upwards towards the engine part 3 and rotated as indicated by the arrows in figure 6c in order to attach the attachment means 46, 47 to the mating structure 50. This has already been done for a second filter unit 40b in figure 6c.

In this case the mating structure 50 comprises two grooves arranged opposite to each other into which the attachment means 46, 47 are introduced by turning the sleeve 41. The grooves have a dead end so that further (clockwise) turning is prevented when the attachment means 46, 47 are properly positioned. The attachment means 46, 47 and the mating structure 50 can, however, be arranged in various ways. In this example it is possible to attach the sleeve 41 to the engine part 3 before connecting the filter unit 40 operatively to the engine, but it may be preferred to make sure that the filter unit 40 is properly connected before attaching the wall/sleeve 41.

The wall/sleeve 40 may be attached directly after connection of the filter unit 40 but may alternatively be attached just before change of the filter unit 40. When the filter unit 40b (see figure 6c) is disconnected from the engine 1 by turning and unthreading the filter housing 12 (while at the same time avoiding turning the sleeve 41), the filter unit 40b will be held in place (with the filter housing 12 in a slightly lower position than when connected) hanging in the attachment means 46, 47 attached to the mating structure 50 in the engine 1. After some time, when the oil has run or dropped down into the reservoir formed by the sleeve/wall 41 above the first end 16 of the filter housing 12, the wall/sleeve 41 can be detached and the filter unit 40 removed.

The filter unit 40 can be provided with a resilient arrangement or a locking arrangement that keeps the sleeve 41 in the upper position (active state) after the attachment means 46, 47 have been detached from the engine 1. This way it can be avoided that the sleeve 41 accidentally falls/slides down after disconnection and detachment of the filter unit 40 which would result in that leakage oil present in the reservoir inside the sleeve 41 runs out.

In the examples shown here, each of the filter housing 12 and the filter chamber inside has a general shape of a cylinder with a common longitudinal axis extending in a direction between the first end 16 to second, opposite end 13, wherein the outlet (or inlet) opening 15 is centrally positioned at the first (upper) end 16 and wherein a plurality of inlet (or outlet) openings 14 are positioned radially outwards of the outlet (or inlet) opening 15. Further, the filter housing 12 comprises a filter element adapted to fit into the filter chamber, wherein the filter element has a longitudinally extending inner cavity that is in communication with the centrally arranged opening 15 but not with the other openings 14 such as to force oil that flows from the inlet to the outlet to pass the filter element.

The invention is not limited by the embodiments described above but can be modified in various ways within the scope of the claims. For instance, the examples shown in figures 2-5 can be provided with attachment means in line with what is described for the example shown in figure 6, i.e. attachment means allowing attachment of the filter unit via the cylindrical wall to the engine. Further, the example shown in figure 6 can be provided with a resilient arrangement in line with what is described for the examples in figures 2-5, i.e. a resilient arrangement that automatically sets the cylindrical wall in its active state when the filter unit is disconnected from the engine.

Further, the resilient elements 33 in figure 5 can be replaced by another resilient arrangement configured to be compressed between the flange 34 (or another detail) and the sleeve 31 , such as a large spring coil that surrounds the filter housing. With such a spring coil the filter unit would be rather similar to the example shown in figure 4 but with the spring coil substituting the wall structure 23.