GB2376426A

GB2376426A - An oil filter arrangement for an internal combustion engine

Info

Publication number: GB2376426A
Application number: GB0114656A
Authority: GB
Inventors: Robert Stephen Mules
Original assignee: Sogefi Filtration Ltd
Current assignee: Sogefi Filtration Ltd
Priority date: 2001-06-15
Filing date: 2001-06-15
Publication date: 2002-12-18
Also published as: GB0213747D0; GB2374298A; GB0114656D0; WO2002103170A1

Abstract

An internal combustion engine 10 comprising an engine block 12, a crank shaft 14, an oil pan 20 defining an oil sump 26, an oil pump 50 and an oil filter unit 30 disposed in the oil sump 26. The filter unit 30 mounts a filter element 32 which is preferably comprised of a paper, felt or synthetic material or similar and is preferably a concertina fold filter element. The surface area of the filter element 32 is chosen such that, during the life time of the engine, the filter element 32 does not need to be replaced due to blockage. The oil filter unit may be attached to the suction side or to the pressure side of the oil pump 50. To protect the oil pump 50 a strainer 48 comprising of a plastic or wire mesh may be attached to an end of the oil inlet pipe 44.

Description

FILTER ARRANGEMENT

This application relates to oil filter arrangements for internal combustion engines. 5 In an internal combustion engine oil is usually drawn up from an oil sump positioned at the base of the internal combustion engine through an inlet pipe to a pump, forced through an oil filter unit, and then distributed to various components in the engine to lubricate and cool. The oil then returns to the oil sump, usually under gravity. Oil used to lubricate and cool must be filtered in order to keep the oil clean 10 and thus working efficiently. Generally the oil filter unit is positioned upstream of the oil pump (i.e. on the pressure side) such that before oil is distributed to components in the engine, it passes through the filter so that it is cleaned. Usually the oil filter unit is attached to the outside of the engine and is required to be replaced every 1 O,OOO-2O,OOO miles or so because of its small size. There has recently been a 15 drive to reduce the space which the oil filter unit takes up in the engine compartment.

Larger pieces of debris can find their way into the oil sump. To prevent such debris from being sucked into the oil pump and damaging the oil pump, a coarse strainer is often positioned at the end of the inlet pipe in the oil sump.

An object of the present invention is to provide an improved filter 20 arrangement. More particularly, it is an object of the present invention to provide a filter arrangement in which the filter of an internal combustion engine takes up no external space on the engine itself or in the engine compartment.

A first aspect of the present invention provides an internal combustion engine comprising: an internal combustion engine comprising: an engine block; an oil pan 25 defining an oil sump, said engine block and said oil pan together defining a sealed unit; and an oil filter unit, wherein said oil filter unit is disposed within said sealed unit. In this way, the overall volume of an internal combustion engine with oil filter unit is decreased because the oil filter unit is disposed in the oil sump. This 30 saves space in the engine compartment and there is no need for a separate oil filter

unit, typically attached to the side of the engine. The space where the oil filter unit is housed in the present invention is otherwise wasted space. The depth of the oil sump may need to be increased fractionally in order that the filter unit can be housed in the oil sump but this increase in volume is marginal.

5 In the hereinafter described embodiments, the volume of space taken up by a filter unit can be as little as the solid volume of the oil filter unit because, if the oil filter unit is at least partly submerged in the oil in the oil sump, the amount of oil displaced is equal to only the solid volume of the individual components of the oil filter unit which is significantly less than the external volume of the oil filter unit due 10 in part to the porous nature of the filter element.

Furthermore, fewer oil galleries are required in the engine block because the oil of the internal combustion engine does not need to leave the engine block to pass through an external filter unit. There are also advantages to disposing the filter unit in the oil sump relating to the construction of the filter unit. For example, any oil 15 leaks from the oil filter unit are less of a problem when the oil filter unit is disposed in the oil sump than when it is disposed externally of the internal combustion engine and so the construction requirements of the filter unit are less stringent.

Preferably the internal combustion engine of the hereinafter described embodiments is for a car and the oil filter unit comprises a filter element which has a 20 surface area of 1 O,OOOmm2 or greater and/or a volume of 1 5,000mm3 or more.

In this way the lifetime of the filter unit can be chosen by providing a surface area or volume of filter element to match the lifetime of the engine. This is a significant advantage, because it means that the oil filter does not need to be replaced during routine maintenance allowing the internal combustion engine to be a sealed 25 unit. In general sumps are sufficiently large to accommodate large filter elements providing a long lifetime. Furthermore, with a large area the pressure drop across the filter unit is kept low and a lower velocity of oil per unit area through the filter unit can be achieved than previously possible.

Preferably the oil filter unit of the internal combustion engine of the present 30 invention has a planar filter element which extends across the sump.

In this way the surface area of the filter element of the oil filter unit may be maximised for a given oil sump size because the filter element may extend across the entire upper surface of the oil in the oil sump.

Preferably the filter unit has a housing made of thermoplastic, thermosetting, 5 or metal material. Thus, the cost of the filter unit can be reduced.

Preferably the internal combustion engine of the present invention further comprises an oil pump for pumping oil from said oil sump around said engine, wherein the oil pump is disposed in the oil pan. In this way, the volume taken up by the internal combustion engine and oil circulation system comprising the oil filter 10 unit and oil pump can be minimised. If the pump is disposed in the pan, especially when mounted below the level of oil, the pump is protected by the oil and the noise vibration harshness (NVH) of the oil pump is also reduced because they are damped by the oil in the oil sump. Also priming of the oil pump on starting the engine is more easily achieved.

1 S Preferably in the internal combustion engine of the present invention the filter unit is on the suction side of the oil pump. In this way, oil entering the oil pump can be filtered before entering the pump thereby protecting the pump. This is a particular advantage of having the filter unit being disposed in the oil sump According to a second aspect of the present invention, there is provided an oil 20 filter unit for disposition in a sealed unit defined by an engine block of an internal combustion engine and an oil pan.

According to a third aspect of the present invention there is provided an oil pan defining an oil sump for an internal combustion engine, in combination with an oil filter according to the second aspect of the present invention 25 According to a fourth aspect of the present invention there is provided an internal combustion engine comprising: an internal combustion engine comprising: an oil pan defining an oil sump; and an oil pump disposed within said oil sump.

In this way the volume taken up by the internal combustion engine and oil 30 pump can be minimised because the pump is disposed within the oil sump and does

-4 not take up any extra volume in the engine. Furthermore, when the pump is disposed in the oil sump and is covered by oil in the oil sump, the pump is protected by oil and the noise vibration harshness ( NVU) of the oil primp is reduced because of dam..pin.g by oil in the oil sump. A1SO7 priming of the oil pump on starting the engine is more 5 easily achieved.

According to a fifth aspect of the present invention there is provided a combination of an oil pan for defining an oil sump of an internal combustion engine and an oil pump, and said oil pump being disposed in said oil sump.

According to sixth aspect of the present invention there is provided an 10 internal combustion engine comprising: an oil pan defining an oil sump; and at least one heat transfer element for the passage of cooling fluid therethrough, said at least one heat transfer element being disposed in said oil sump.

In this way the volume taken up by the oil cooling system in the engine compartment is minimised because the size of external oil cooling systems can be 15 reduced or external cooling systems may even become obsolete.

According to a seventh aspect of the present invention there is provided a combination of an oil pan for defining an oil sump of an internal combustion engine and at least one heat transfer element, said at least one heat transfer element being disposed in said oil sump.

20 Other objects and advantages of the present invention will become apparent from the following description of various embodiments of the present invention with

reference to the following drawings in which: Figure 1 is a cross section through an internal combustion engine in the longitudinal direction of the crank shaft of a first embodiment of the present 25 invention; Figure 2 is a cross section through an internal combustion engine in the transverse direction of the crank shaft of a first embodiment of the present invention; Figure 3 is a cross section through an internal combustion engine in the longitudinal direction of the crank shaft of an internal combustion engine according 30 to a second embodiment of the present invention;

-5 Figure 4 is a cross section through an internal combustion engine in the transverse direction of the crank shaft of a second embodiment of the present invention; Figure 5 is a cross section through an internal combustion engine in the 5 longitudinal direction of the crank shaft of an internal combustion engine according to a third embodiment of the present invention; Figure 6 is a perspective view of a fourth embodiment according to the present invention; and Figure 7 is a cross section through an oil pan for defining an oil sump of an 10 internal combustion engine according to a fifth embodiment of the present invention.

In the figures like reference numerals are used to indicate like components.

Figures 1 and 2 illustrate an internal combustion engine 10 according to the present invention. The internal combustion engine 10 comprises an engine block 12, a crank shaft 14 and an oil pan 20. The oil pan 20 is attached to the bottom of the 15 engine block 12 by conventional means.

The oil pan 20 defines an oil sump 26 and is comprised of side walls 22 and a base wall 24. An oil filter unit 30 is disposed within the oil pan 20. By oil filter unit we mean a filter unit effective as a filter for the purpose of filtering engine oil for circulation through an internal combustion engine. This contrasts with a strainer 20 which typically comprises a wire mesh with pores of about lmm2 and is provided to strain large pieces of debris from the oil to prevent them from entering the oil pump.

The filter unit 30 mounts a filter element 32 which is preferably comprised of a paper, felt or synthetic material or similar and is preferably a concertina fold filter element thereby maximising its surface area for the amount of space it occupies. The 25 surface area of the filter element 32 is chosen such that, during the life time of the engine, the filter element 32 does not need to be replaced due to blockage.

The filter element 32 may be a normal filter element of approximately 0. 5mm thickness or may be a depth filter element which is typically between 10-20mm thick. In the case of a depth filter element the surface area is preferably at least 30 lOOOOmm2, more preferably 17500mm2 and in the case of a flat filter element the

-6 surface area is preferably at least l OOOOOmm2, more preferably 500000mm2 and still yet more preferably lOOOOOOmm2.

Preferably the surface area is such that the ratio of the surface area of filter element 32 to the surface area of the upper surface of oil in the oil sump 26 is at least 5 1:1.

Furthemmore, the filter element 32 preferably has pores which give filtration levels of 0.05mm or less, more preferably a level of O.Olmm or less and still yet more preferably a level 0.005mm or less.

Preferably the filter element, whether or not it is a flat filter element or a 10 depth filter element, has a volume of at least 150000mm3. More preferably the volume of the filter element is at least 200000mm3, and still yet more preferably is at least 350000mm3. A filter element with such a size should last for about 100000 miles. If the filter element should last for about 150000 miles, which is the presently designed range of internal combustion engines, the filter element should preferably 15 have a volume of at least 500000mm3.

A typical flow rate of oil through a filter element in a typical car internal combustion engine is about 20 litres/minute. The filter element of the present invention preferably has a volume of at least l OOOOmm3 per litre/minute of flow of oil designed, for a given engine, to flow through the filter element 32. More 20 preferably, the filter element has a volume of at least 1 7500mm3 per litre/minute and still yet more preferably of at least 20000mm3 per litre/minute.

A further advantage of the filter unit 30 is that because of the large surface area of the filter element 32, the oil pressure drop over the filter element 32 is kept low. Also, the pores of the filter element 32 can be reduced in size in comparison to 25 filter elements which are external to the engine block 12 because of the increase of surface area of the filter element 32 in comparison to those filters external of the engine block 12. Thus smaller contamination in the oil may be filtered out than previously and so the efficiency of the oil as a lubricant and/or coolant can be maximised as well as the useful lifetime of the oil being extended.

30 In the embodiment illustrated in Figure 1, the filter element 32 of the filter

-7 unit 30 is housed in a filter housing 34. Preferably the filter element 32 is a planer concertina fold filter element as opposed to an annular concertina fold filter element such that the filter element may extend across the oil sump and be housed in a planar housing 34. Because the filter unit is disposed in the oil sump which the housing 34 5 of the filter unit 30 may be made of a polymer or plastics material, thermoplastic, thermosetting or metal. Furthermore, planar housings are easier to manufacture than cylindrical housings and may be, for example, snap fitted together. However, planar housings are only preferred and any other type of housing such as cylindrical may also be used.

10 The housing 34 is provided with flanges 36 through which the filter unit 30 may be attached to the internal combustion engine 10. In the embodiment illustrated in Figure 1, this is achieved by bolting flanges 36 to attachment members 42 which are part of the engine block 12. In an alternative embodiment, illustrated in Figures 5,6 and 7, the filter unit 30 attached to the oil pan 20 by bolting the flanges 36 of the 1 S filter housing 34 to attachment members 42 extending upwards from the base wall 24 of the oil pan 20. It will be immediately apparent to those skilled in the art that there are other ways of attaching the filter unit 30 to the oil pan 20 or to the engine block 12. The filter unit 30 is provided with an inlet 38 and an outlet 40. The filter unit 20 30 is below the surface of the oil in the oil sump 26 or at least partly submerged.

This ensures that the volume occupied by the filter element is only the total of the volumes of the solid individual components of the filter unit 30 rather than the external volume of the filter unit 30.

The oil in the oil sump 26 is distributed to various parts of the internal 25 combustion engine to provide cooling and lubrication by a pump 50 which is optionally housed in the internal combustion engine 10. In the embodiment illustrated in Figure 1, the oil pump 50 is situated partly in the engine block 12 and partly in the oil sump 26. The pump 50 may be situated entirely within the engine block 12 or entirely within the oil sump 26 and may even be situated at least partly 30 submerged in the oil of the oil sump 26.

-8 In the first embodiment of the present invention as illustrated in Figure 1, the filter unit 30 is attached to the suction side of the oil pump 50. Oil from the oil sump 26 travels through an oil inlet pipe 44 to the inlet 38 of the filter unit 30. Qptiona!!y a strainer 48 comprised of a plastic or wire mesh with a mesh size of greater than 5 0. lmm in diameter may be connected to an end of the oil inlet pipe 44 opposite the end of the oil inlet pipe which is connected to the inlet 38 of the filter unit 30. The end of the oil inlet pipe 44 or the strainer 48 is positioned in a recess 25 formed in the oil pan 20. The recess 25 provides a low point in the base wall 24 of the oil pan 20 in which oil collects. A first pipe 46 connects the outlet 40 of the filter unit 30 to the 10 pump 50. The pump 50 then pumps the oil to the various components such as the rocker spindles, gudgeon pins and crank shaft bearings in the internal combustion engine 10. The oil returns to the oil sump 26 under gravity.

The positioning of the filter unit 30 before the oil pump 50 in the oil circuit is advantageous in that the pump 50 is protected from contaminants present in the oil 15 such as swaths of metal etc. A second embodiment according to the present invention is illustrated in Figures 3 and 4 which is the same as the first embodiment save as described below.

In this embodiment the filter unit 30 is attached to the pressure side of the oil pump 50 and an oil inlet pipe 144 provides for the passage of unfiltered oil from the oil 20 sump 26 into an inlet of the oil pump 50. To protect the oil pump 50 a strainer 48 is attached to an end of the oil inlet pipe 144 opposite to the end which is attached to the oil pump 50. The oil pumped by oil pump 50 is routed via a second pipe 244 to the inlet 38 of the filter unit 30. That oil passes through the filter element 32 before being routed around the engine via a first pipe 46 which provides for the passage of 25 oil from the outlet 40 of the filter unit 30.

The filter unit 30 of the present invention may include a non-return valve which prevents oil from draining out of the filter housing 34 through the inlet 38 which if allowed to happen, would introduce a delay in oil being supplied around the engine on start-up.

30 The filter unit 30 may also comprise a by-pass valve for the flow of oil by

-9- passing the filter element 32 in the case when the pressure drop across the filter element 32 rises above a predetermined value. This allows oil to flow through the filter unit 30 around the engine even if the filter element 32 has become blocked with dirt. The filter unit 30 may also comprise a pressure relief valve.

5 Figure 5 illustrates a third embodiment of the present invention which is the same as the first and second embodiments save as described below.

In this embodiment the filter unit 30 is attached to the pressure side of the oil pump 50 in the same way as in the second embodiment. However, in this case, the filter unit housing 34 is attached to the oil pan 20. Also two filter elements 132, 232 10 are housed in the housing 34. The filter element 132 is a full flow filter element which has the same properties as the filter element 32 of the second embodiment.

Oil which passes through full flow filter element 132 exits the filter housing 34 via a first pipe which provides for the passage of oil from a first outlet 140 associated with the full flow filter element 132 around the engine.

15 A fraction of the oil entering the filter unit housing 34 from second pipe 244 passes through a by-pass filter element 232. Typically the fraction of oil directed through the by-pass filter unit 232 is about 10% of the total oil which passes through the second pipe 244 but may be any fraction depending on the relative resistance of the by-pass filter element 232 and full flow filter element 132. In this way, the by 20 pass filter element 323 may be provided with pores of a particularly small diameter, for example, to give filtration levels of less than 0.001mm. In this way, the oil which is filtered by the by-pass filter element 232 is thoroughly clean. This thoroughly clean oil is returned to the oil sump 26 directly via by-pass tube 146.

Although in the third embodiment the by-pass filter element 232 and the full 25 flow filter element 132 are housed in the same housing, this is not necessarily the case. Furthermore, it is possible that the full flow filter element 132 is connected to the suction side of the oil pump 50 rather than the pressure side as is illustrated.

Then a fraction of oil leaving the oil pump 50 would enter the by-pass filter element 232 and return to the oil sump 26 whilst the remaining fraction of oil leaving the oil 30 pump 50 would be directly routed around the engine in a similar way to that in the

-10 first embodiment.

In the third embodiment, the oil pump 50 is disposed within the oil sump 26 defined by the oil pan 20. The oil pump 50 is actually beneath the level of oil 126 in the oil sump 26. In this way noise-vibrationharshness (NVH) of the oil pump 50 5 may be reduced thus decreasing engine noise and increasing oil pump lifetime. The oil pump 50 may be attached to the oil pan 20 or to the engine block 12. Although the oil pump 50 is illustrated as being entirely below the level 126 of oil in the oil sump 26 this is not necessarily the case and the oil pump 50 may only be partially submerged whilst still maintaining the advantages described above.

10 A fourth embodiment of the present invention is illustrated in Figure 6 which is the same as the first and second embodiments save as described below. In this embodiment the filter unit 30 is disposed on the pressure side of the oil pump 50. Oil leaves the oil filter pump via a first portion of a second pipe 244A. The first portion of the second pipe 244A leads to a heat exchanger 300. A second portion of the 15 second pipe 244B leads from the heat exchanger 300 to the oil filter unit 30. The heat exchanger 300 is attached to the housing 34 ofthe oil filter unit 30 via fasteners 320. The heat exchange 300 contains at least one heat transfer element for the passage of cooling fluid therethrough. Cooling fluid enters the heat exchanger 300 20 through inlet 310 and leaves the heat exchanger 300 through outlet 312. Inlet 310 and outlet 312 extend through the oil side walls of the oil pan 20. The heat transfer elements inside the heat exchanger 300 may be of any size and shape. Oil which travels through the heat exchanger 300 will come into contact with the heat transfer elements and thereby be cooled by the heat transfer fluid flowing through those 25 elements. Thus oil is routed by channels and forced by the oil pump 50 past the at least one heat transfer element.

In the embodiment illustrated in Figure 6 the heat transfer unit 300 and oil filter unit 30 are illustrated on the pressure side of the oil pump 50. This is not necessarily the case and either the oil filter unit or the heat transfer unit 30 or both 30 may be positioned on the suction side of the oil pump 50. In fact, oil need not

-11 necessarily be purposefully routed past the heat transfer elements; the heat transfer elements may simply be positioned in the oil sump and rely on natural mixing of oil in the oil sump for efficient cooling.

An oil pan according to a fifth embodiment is illustrated in Figure 7. The oil 5 filter unit SO, the heat transfer unit 300 and the pump 50 are all disposed in the oil sump defined by the oil pan 20. Indeed those three components are all below the level of oil 126 in the oil sump 26 and all are attached to the oil pan 20. The oil pan of the fifth embodiment may be mounted to an engine block 12 as in the first to fourth embodiments.

10 Although five separate embodiments have been described above, it will be apparent to those skilled in the art, that features of each embodiment may be combined with features of other embodiments as required.

Claims

-12 Claims

1. An internal combustion engine comprising: an engine block; 5 an oil pan defining an oil sump, said engine block and said oil pan together defining a sealed unit; and an oil filter unit, wherein said oil filter unit is disposed within said sealed unit.

10

2. An internal combustion engine according to Claim 1, wherein said oil filter unit includes a filter element.

3. An internal combustion engine according to Claim 2, wherein said filter element has pores which give filtration levels below 0.05mm or less.

4. An internal combustion engine according to Claim 2 or 3, wherein said filter element is a concertina fold filter element.

5. An internal combustion engine according to any one of Claims 2 to 4, 20 wherein said filter element has a total surface area of 1 OOOOmm2 or greater.

6. An internal combustion engine according to any one of Claims 2 to 5, wherein said filter element has a volume of 15000mm3 or more.

25

7. An internal combustion engine according to any one of Claims 2 to 6, wherein said internal combustion engine is constructed and arranged for oil flow therethrough, at least part of said oil flow being through said filter element, and said filter element has a volume of at least 1 OOOOmm3 per litre/minute of flow of oil through said filter element.

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8. An intemal combustion engine according to any one of Claims 2 to 7, wherein said filter unit further comprises a by-pass valve for by- passing the filter element when the pressure drop across the filter element rises above a predetermined value.

9. An intemal combustion engine according to any one of Claims 2 to 8, wherein said filter element is a planar filter element extending across said oil sump.

10. An intemal combustion engine according to claim 9, wherein said filter 10 element is housed in a planar housing.

11. An intemal combustion engine according to any of claims 2 to 10, wherein said filter element in a depth filter element.

1 S

12. An intemal combustion engine according to any one of the preceding Claims, wherein said filter unit further comprises a pressure relief valve.

13. An intemal combustion engine according to any one of the preceding Claims, wherein said filter unit includes a non-return valve for preventing oil from flowing 20 out of said oil filter unit under gravity.

14. An internal combustion engine according to any one of the preceding claims, wherein said oil filter unit is disposed in the oil sump.

25

15. An intemal combustion engine according to Claim 14, wherein said filter unit is at least partially submerged in oil in said oil sump.

16. An intemal combustion engine according to any one of the preceding Claims, wherein said filter unit has a housing made of thermoplastic, thermosetting, or metal 30 material.

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17. An internal combustion engine according to any one of the preceding Claims, further comprising an oil pump for pumping oil from said oil sump through said filter and around said engine.

5

18. An internal combustion engine according to Claim 17, wherein said oil pump is disposed in said oil pan.

19. An internal combustion engine according to Claim 17 or 18, wherein said oil filter unit is connected on the pressure side of said oil pump.

20. An internal combustion engine according to any one of Claimsl 7 or 18, wherein said filter unit is connected on the suction side of said oil pump.

21. An internal combustion engine according to Claim 19 or 20, further l S comprising a by-pass filter unit connected on the pressure side of said oil pump, said by-pass filter having a filter element with pores effective to give a filtration to levels O.OOlmm and below.

22. An internal combustion engine according to Claim 21, wherein flow passages 20 guide a fraction of oil leaving said pump through said bypass filter unit and then to said sump.

23. An internal combustion engine according to claim 21 or 22, wherein said by-

pass filter is disposed in said sealed unit.

24. An internal combustion engine according to Claim 23 wherein said bypass filter is disposed in said oil sump.

25. An internal combustion engine according to Claim 24, wherein said bypass 30 filter is disposed at least partly beneath the level of oil in said oil sump.

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26. An internal combustion engine according to any one of claims 21 to 25, wherein said by-pass filter unit is housed in the same housing as said filter unit.

27. An internal combustion engine according to any one of Claims 17 to 26, S further comprising a strainer with a mesh size of 0. lmrn or greater in diameter connected to the suction side of said pump.

28. An internal combustion engine according to any one of the preceding Claims, further comprising at least one heat transfer element for the passage of cooling fluid 10 therethrough disposed in said oil sump.

29. An oil filter unit for disposition in a sealed unit defined by an engine block of an internal combustion engine and an oil pan.

1 S

30. An oil filter unit according to Claim 29, including a filter element.

31. An oil filter unit according to Claim 27, wherein said filter element has pores effective to give filtration to a level of 0.05mm or less.

20

32. An oil filter unit according to Claim 30 or 31, wherein said filter element has a total surface area of I OOOOmm2 or greater.

33. An oil filter unit according to any one of Claims 30 to 32, wherein said filter element has a volume of 15000mm3 or more.

34. An oil filter unit according to any one of Claims 29 to 33, wherein said filter unit further comprises a pressure relief valve.

35. An oil filter unit according to any one of Claims 29 to 34, wherein said filter 30 unit includes a non-return valve for preventing oil from flowing out of said oil filter

-16 unit under gravity.

36. An oil filter unit according to any one Of laim.s 99 to 35, wherein said filter unit has a housing made of thermoplastic, themmosetting resin, or metal material.

37. An oil pan defining an oil sump for an internal combustion engine in combination with an oil filter unit according to any one of claims 29 to 36.

38. An internal combustion engine comprising: 10 an oil pan defining an oil sump; and an oil pump disposed within said oil sump.

39. An internal combustion engine according to claim 38, wherein said oil pump is mounted to said oil pan.

40. An internal combustion engine according to claims 38 or 39, wherein said oil pump is at least partly below the level of oil in said oil sump.

41. An internal combustion engine according to claim 40, wherein said oil pump 20 is entirely below the level of oil in said oil sump.

42. A combination of an oil pan for defining an oil sump of an internal combustion engine and an oil pump, and said oil pump being disposed in said oil sump.

43. An internal combustion engine comprising: an oil pan defining an oil sump; and at least one heat transfer element for the passage of cooling fluid therethrough, said at least one heat transfer element being disposed in said oil sump.

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44. An intemal combustion engine according to claim 43, wherein said at least one heat transfer element is mounted to said oil pan.

45. An internal combustion engine according to claims 40 or 41, wherein an inlet S and an outlet for cooling fluid entering and leaving said at least one heat transfer element are disposed in a wall of said oil pan.

46. A combination of an oil pan for defining an oil sump of an internal combustion engine and at least one heat transfer element, said at least one heat 10 transfer element being disposed in said oil sump.

47. A combination according to claim 46, wherein said at least one heat transfer element is mounted to said oil pan.

1 S

48. A combination according to claims 46 or 47, wherein an inlet and an outlet for cooling fluid entering and leaving said at least one heat transfer element are disposed in a wall of said oil pan.

49. An internal combustion engine according to any one of claims 28 or 43 to 45 20 or a combination of claim 46 or 47, wherein said heat transfer elements are housed in a heat exchanger.

50. An internal combustion engine or a combination according to claim 49, further comprising flow passages for directing oil through said heat exchanger.

S 1. An oil filter unit substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

52. An oil pan substantially as hereinbefore described with reference to and as 30 illustrated in the accompanying drawings.

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53. An internal combustion engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.