FUEL TANK

TECHNICAL FIELD

The present invention relates to an internal combustion engine tank assembly comprising a first casing defining a first enclosed volume. The first enclosed volume comprises a first outlet adapted to be in fluid communication with a fuel supply line of an internal combustion engine system. The tank assembly further comprises a second casing forming a second enclosed volume comprising a second outlet adapted to be in fluid communication with a conduit system of an operation fluid of the engine system.

The invention also relates to an internal combustion engine system comprising such a tank assembly as well as a vehicle comprising such an engine system and/or tank assembly.

BACKGROUND OF THE INVENTION In the field of internal combustion engines, and in particular in diesel engines, it is generally desired to obtain appropriate temperature intervals for fluids which are used in the engine. Examples of such fluids include but are not limited to: a fuel to the engine; a lubricant and, in the case of a diesel engine, a reactive fluid for treatment of exhaust gases from the diesel engine. The appropriate temperature interval may differ between different fluids in the engine but as a general remark, the freezing point of a fluid may define the lowermost allowable temperature for a fluid whereas the boiling point of the fluid may define the uppermost allowable temperature of the aforesaid temperature interval. Naturally, an appropriate temperature interval may be narrower than ranging between the extreme points defined above. Purely by way of example, if urea is used as a reactive fluid for treatment of exhaust gases in a diesel engine, it is generally desired that the temperature of the urea is kept below approximately 60 ⁰ C, above which temperature decomposition phenomena of the urea may arise. Furthermore, instead of using the freezing point of a fluid as the lowermost point in a temperature interval, a lowermost temperature may instead correspond to a maximum allowable viscosity of the fluid. In particular, should the ambient temperature of an internal combustion engine be low, e.g. - 20 ⁰ C, it is generally desired to rapidly increase the temperature of the fuel prior to or during operation of the engine.

In order to control the temperatures of two fluids which are used in an internal combustion engine, EP 1 645 452 A1 proposes a storage system including a fuel tank and a urea tank. The fuel tank is provided with a fuel supply line to the engine and a fuel return line from the engine. In operation, fuel returned from the engine will be fed to the fuel tank through the fuel return line. Since the return fuel generally is heated during its transport to and from the engine, the temperature of the fuel in the tank will increase until the fuel in the tank has reached the same temperature as the return fuel. Furthermore, '452 A1 teaches that the urea tank is arranged such that the fuel and urea tanks are able to reciprocally exchange heat and preferably the urea tank is located in a concavity of the fuel tank. As such, as the fuel in the fuel tank is heated according to the procedure described above, the urea in the urea tank will be heated correspondingly due to the heat exchange between the fuel tank and the urea tank. Thus, the urea is also heated to an appropriate temperature.

However, there is still need for improvements of internal combustion engine tank assemblies. For instance, the urea tank of the '452 A1 storage system will be heated by the fuel in the fuel tank during operation, but it is not likely that the urea tank will transfer heat back to the fuel when the engine is not in an operation mode. Thus, once the engine has been shut down, the temperature of the fuel in the fuel tank will decrease rapidly to the temperature ambient of the fuel tank. In particular, if the ambient temperature is low, e.g. below -20° C, the function of the engine may be impaired if the fuel attains the ambient temperature when started.

Furthermore, an increasing problem for owners and/or operators of trucks or heavy vehicles is that fuel is stolen from the tank by a procedure wherein the thief simply drills a hole into the fuel tank and empties the fuel tank from fuel. Such operations cannot generally be prevented by the '452 A1 storage system.

SUMMARY OF THE INVENTION A first object of the invention is to provide a tank assembly for an internal combustion engine, which provides a slow decrease of the temperature of fuel once the engine has been shut down.

A second object of the invention is to provide a tank assembly for an internal combustion engine, which aggravates theft of fuel by drilling a hole in the tank assembly.

A third object of the invention is to provide a tank assembly for an internal combustion engine, which provides for a rapid heating of an operation fluid in a tank located close to the fuel tank.

At least one of the aforementioned objects is achieved by an internal combustion engine tank assembly according to claim 1.

Thus, the invention relates to an internal combustion engine tank assembly comprising a first casing defining a first enclosed volume. The first enclosed volume comprises a first outlet adapted to be in fluid communication with a fuel supply line of an internal combustion engine system. The tank assembly further comprises a second casing forming a second enclosed volume comprising a second outlet adapted to be in fluid communication with a conduit system of an operation fluid of the engine system. According to the invention, the second casing substantially encloses the first casing such that the second enclosed volume is defined between an outer surface of the first casing and an inner surface of the second casing.

As such, since the second enclosed volume is substantially enclosing the first enclosed volume, the heat exchanging interaction between the two volumes is enhanced. Particularly, the operation fluid which may be stored in the second enclosed volume may be heated by the fuel during operation of the engine whereas the heated operation fluid in turn may decelerate the temperature decrease of the fuel when the engine has been shut down.

Moreover, if a person were to drill a hole in the tank assembly in order to appropriate for himself fuel accommodated in the first enclosed volume, he would obtain a mixture of fuel and operation fluid, which mixture is not suitable as fuel. Should the mixture be used for an internal combustion engine, the mixture may in fact damage the engine. As such, the tank assembly of the present invention may prevent fuel theft.

Additionally, since the tank assembly of the present invention presents the capability of storing an operational fluid as well as the theft prevention advantage as presented

hereinabove, a space-saving assembly has been obtained. As such, rather than providing a fuel tank with separate operational fluid storing and fuel theft preventing arrangements, these two arrangements are jointly obtained by the tank assembly of the present invention. Thus, a compact arrangement may be obtained which may require less space in an internal combustion engine system, or on a vehicle onto which the engine system is mounted. Optionally, or additionally, the compactness of the tank assembly of the present invention may instead provide for that the fuel tank, i.e. the first enclosed volume, can be made larger as compared to systems wherein heating and fuel theft preventing arrangements are provided separately.

As used herein, the expression "substantially enclosing" should be interpreted such that a major part of the outer surface of the first casing is covered by the second casing. Some embodiments of the tank assembly of the invention may be referred to as a double bottom tank wherein the second casing completely covers the first casing. However, the expression "substantially enclosing" also encompasses tank assemblies wherein a minor portion of the first casing is not covered by the second casing.

As used herein, the expression "operation fluid" should be interpreted as a fluid which is not the fuel of the engine but which nevertheless is used in the operation of the internal combustion engine. Purely by way of example, an operation fluid may be: a lubricant; a cooling liquid, or a reactive fluid for treatment of exhaust gases from the engine.

According to a preferred embodiment of the invention, the second enclosed volume comprises a coolant conduit. The coolant conduit is adapted to be in fluid communication with a cooling system of the engine system. Thus, the operation fluid accommodated in the second enclosed volume may be additionally heated by the coolant conduit which may provide for more rapid heating of the operation fluid in the second enclosed volume which in turn will affect the temperature of the fuel in the first enclosed volume.

According to a further embodiment of the invention, the second enclosed volume comprises a return fuel conduit. The return fuel conduit comprises a return fuel inlet and a return fuel outlet wherein the return fuel inlet is adapted to be in fluid communication with a return fuel line of the engine system and the return fuel outlet is in fluid communication with the first enclosed volume. In particular, when the operation fluid in the second enclosed volume is intended to be heated by the fuel in the first enclosed volume, this

embodiment is preferred. As such, rather than heating the operation fluid by the fuel in the first enclosed volume which in turn may be heated by return fuel, the operation fluid may be heated directly by the return fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be further explained by means of non-limiting examples with reference to the appended figures wherein:

Fig. 1 is a schematic view of an internal combustion engine system of the prior art;

Fig. 2 is a perspective view of the internal combustion engine tank assembly according to the present invention;

Fig. 3 is a perspective view of the Fig. 2 tank assembly, when mounted on a truck;

Fig. 4 is a schematic view of an internal combustion engine system comprising an embodiment of the tank assembly of the present invention;

Fig. 5 is a cross-sectional view of the Fig. 4 embodiment of the tank assembly of the present invention, and;

Fig. 6 is a schematic view of an internal combustion engine system comprising a further embodiment of the tank assembly of the present invention;

Fig. 7 is a cross-sectional view of the Fig. 6 embodiment of the tank assembly of the present invention;

Fig. 8 is a cross-sectional view of another embodiment of a tank assembly of the present invention, and

Fig. 9 is a cross-sectional view of still another embodiment of a tank assembly of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention will, in the following, be exemplified by embodiments. It should however be realized that the embodiments are included in order to explain principles of the invention and not to limit the scope of the invention, defined by the appended claims.

Fig. 1 illustrates a schematic view of a general internal combustion engine system 10, known to persons skilled in the art. The internal combustion engine system 10 illustrated in Fig. 1 is preferably mounted on a heavy vehicle or a truck. The internal combustion engine system 10 comprises an internal combustion engine 12, which preferably is a diesel engine. The system 10 comprises a fuel tank 14 for storing and supplying fuel and the fuel tank 14 is in fluid communication with the engine 12 by means of a fuel supply line 16 and a fuel return line 18. Fuel returned from the engine 12 to the fuel tank 14 through the fuel return line 18 generally has a temperature which is higher than the temperature of the fuel supplied to the engine 12 through the fuel supply line 16.

The temperature increase of the fuel returned to the fuel tank 14 may be achieved in a plurality of ways. For example, the fuel may be heated by the cylinder head of the engine 12 prior to being returned to the fuel tank 14 through the fuel return line 18. Furthermore, the engine 12, particularly if it is a diesel engine, may comprise a high pressure fuel pump (not shown) located between the fuel supply line 16 and a fuel injection system (not shown) of the engine 12. As the fuel is compressed by the fuel pump, the temperature of the fuel is increased prior to being conducted to the injection system. Hence, the return fuel, which does not enter the injection system, will also obtain a temperature increase before being returned to the tank 14 through the fuel return line 18.

The engine system 10 illustrated in Fig. 1 further comprises a cooling system 20 comprising first and second cooling lines 22, 24 connected to cooling channels (not shown) in the engine 12. The cooling system 20 is filled with coolant, preferably water, and further comprises a heat exchanger 26 in fluid communication with the first and second cooling lines 22, 24. The heat exchanger 26 is adapted to emit heat to the ambient air. Additionally, the cooling system 20 comprises a coolant pump (not shown) adapted to drive the coolant around inside the cooling system 20. As indicated in Fig. 1, the operating direction of the coolant pump is such that coolant heated by the engine 12

will in turn be conducted through the first cooling line 22; the radiator 26 and finally the second cooling line 24 before re-entering the engine 12. As such, the temperature of the coolant in the first cooling line 22 is generally higher than the temperature of the second cooling line 24 whenever the engine 12 is running.

As may be gleaned from Fig. 1 , the engine system 10 further comprises an exhaust gas system 28 comprising an exhaust pipe 30. The exhaust gas system 28 further comprises an exhaust gas treatment system 29 comprising an injector 32 adapted to inject a reactive fluid, preferably urea, into the exhaust pipe 30. The exhaust gas treatment system 29 further generally comprises a reactive fluid tank 34 and a reactive fluid line 36 connecting the injector 32 and the reactive fluid tank 34.

Bearing the prior art internal combustion engine system 10 described above in mind, the internal combustion engine tank assembly of the present invention will be described hereinbelow.

Fig. 2 illustrates an embodiment of the internal combustion engine tank assembly 38 of the present invention. The tank assembly 38 comprises a first casing 40 defining a first enclosed volume 42. The first enclosed volume 42 may also be denoted a fuel tank. Purely by way of example, the volume of the fuel tank may be within the range of 200 to 1000 litres (0.2 to 1 m ³ ). As may be gleaned from Fig. 2, the first enclosed volume 42 is provided with a fuel filler pipe 44 which is sealable by a fuel filler cap 46. Furthermore, the first enclosed volume 42 comprises a first outlet 48 adapted to be in fluid communication with the fuel supply line 16 of the engine system 10. The tank assembly further comprises a second casing 50 forming a second enclosed volume 52 between an outer surface of the first casing 40 and an inner surface of the second casing 50. The second volume 52 comprises a second outlet 54 adapted to be in fluid communication with a conduit system of an operation fluid of the engine 12. Purely by way of example, the volume of the second enclosed volume 42 may be within the range of 50 to 200 litres.

The conduit system may be selected from a plurality of conduit systems of the engine system 10. As an example, the conduit system may be the cooling system 20 of the engine in which case the second outlet 54 may be connected to the first cooling line 22 of the cooling system. Optionally, the conduit system may be the exhaust gas treatment

system 29 of the engine system 10. In this case, the second outlet 54 may be connected to the reactive fluid line 36.

As may further be gleaned from Fig. 2, the second casing 50 substantially encloses the 5 first casing 40 such that the second enclosed volume 52 is defined between the first casing 40 and the second casing 50. In the embodiment of the tank assembly 38 of the present invention illustrated in Fig. 2, the second casing 50 completely encloses the first casing 40, i.e. the tank assembly 38 illustrated in Fig. 2 may be regarded as a double bottom tank. It should however be noted that in other embodiments of the tank assembly 10 38 of the present invention, the second casing 50 may not completely enclose the first casing 40. Purely by way of example, the second casing 50 may in some embodiments enclose only 60%, preferably 80%, more preferably 90% of the first casing 40.

The first or inner casing 40 is preferably made of a material having a high thermal 15 conductivity. Purely by way of example, the inner casing 40 may be made of metal, such as steel or aluminium. Furthermore, the second or outer casing 50 may preferably be made of a material having a low thermal conductivity. Purely by way of example, the second casing 50 may be made of a plastics material. Optionally, the tank assembly 38 may be furnished with an insulating material (not shown) enclosing the outer casing 50. 0 Purely by way of example, the second casing 50 may in this case be made of a metal, such as steel, stainless steel or aluminium.

Fig. 3 illustrates the tank assembly 38 according to the present invention, when mounted on a truck 53. 5

Fig. 4 illustrates an internal combustion engine system 10 which comprises an embodiment of the tank assembly 38 of the present invention. As may be gleaned from Fig. 4, in addition to the fuel supply line 16 and the fuel return line 18, the first cooling line 22 is also in fluid communication with the tank assembly 38. 0

Fig. 5 illustrates a cross-sectional view of the Fig. 4 embodiment of the tank assembly 38 of the present invention. As in Fig. 2, the Fig. 5 embodiment comprises an inner and outer casing 40, 50 respectively, such that a first enclosed volume 42 and a second enclosed volume 52 are provided. The first enclosed volume 42 is provided with a first outlet 48 in 5 communication with the fuel supply line 16 of the engine 12. Moreover, the first enclosed

volume 42 comprises a first inlet 56 in fluid communication with the fuel return line 18. As such, whenever the engine 12 is running, fuel 43 will be discharged from the first enclosed volume 42 through the first outlet 48 while, at the same time, the first enclosed volume 42 will be fed by heated fuel from the fuel return line 18. Thus, when the engine is running, the temperature of the fuel 43 in the first enclosed volume 42 will gradually increase until it has reached the temperature of the fuel in the fuel return line 18.

Fig. 5 further illustrates that the second enclosed volume 52 may be provided with a second outlet 54 and a second inlet 58. As previously indicated in conjunction with Fig. 4, in the embodiment illustrated in Fig. 5, the second inlet and outlet, respectively, are connected to the first cooling line 22 of the cooling system 20. Naturally, the second inlet 58 is adapted to be located upstream of the second outlet 54 with respect to the direction of flow in the cooling system 20. Thus, coolant heated by the engine 12 will pass the second enclosed volume before entering the heat exchanger 26. Thus, an increased heating of the fuel 43 in the first enclosed volume 42 may be obtained due to the heat exchange between the coolant in the second enclosed volume 52 and the fuel in the first enclosed volume 42. In order to avoid obtaining to high a temperature of the fuel in the first enclosed volume 42, the tank assembly 38 may preferably be provided with a control arrangement (not shown) for regulating the flow and/or temperature of the coolant passing through the second enclosed volume 52. Purely by way of example, such a control arrangement may comprise a by-pass arrangement (not shown) having a by-pass valve (not shown). As such, when the temperature of the coolant exceeds a predetermined value, the coolant no longer passes the second enclosed volume 52.

When the engine 12 has been shut down, the second enclosed volume 52 will be filled with heated coolant, assuming that the engine has been run for a while. As such, the decrease of the temperature of the fuel 43 in the first enclosed volume 42 to the temperature ambient of the tank assembly 38 will be delayed. Furthermore, should a person, attempting to steal the fuel 43 in the first enclosed volume 42, drill a hole in the tank assembly 38 he would obtain a mixture of coolant and fuel 43.

Fig. 6 illustrates an internal combustion engine system 10 which comprises a further embodiment of the tank assembly 38 of the present invention. As may be gleaned from Fig. 6, in addition to the fuel supply line 16 and the fuel return line 18, the reactive fluid line 36 is also in fluid communication with the tank assembly 38.

Fig. 7 illustrates a cross-sectional view of the Fig. 6 embodiment of the tank assembly 38 of the present invention. In the Fig. 7 embodiment the second enclosed volume 52 is adapted to accommodate a reactive fluid, preferably urea, to be used in the exhaust gas treatment system 29. As such, the second enclosed volume 52 is provided with a filler pipe 60 through which the second enclosed volume 52 may by filled with the reactive fluid. Furthermore, the second outlet 54 of the Fig. 7 tank assembly 38 is connected to the reactive fluid line 36. As such, the second enclosed volume 52 in the embodiment illustrated in Fig. 7 in fact constitutes the reactive fluid tank 34 illustrated in Fig. 1 of the exhaust gas treatment system 29.

When the engine 12 is running, the fuel 43 will be heated by the returned fuel from the fuel return line 18 as previously discussed in conjunction with the embodiment illustrated in Figs. 4 and 5. Thus, the reactive fluid in the second enclosed volume 52 will also experience a temperature increase due to the heat exchange between the first and second enclosed volumes 42, 52. In a similar manner as for the Fig. 5 embodiment, when the engine 12 has been shut down, the heated reactive fluid in the second enclosed volume 52 will delay the temperature decrease of the fuel 43 in the first enclosed volume 42. Furthermore, should a person, in an attempt to steal the fuel 43 in the first enclosed volume 42, drill a hole in the tank assembly 38 he would obtain a mixture of reactive fluid and fuel 43.

Fig. 8 illustrates a further implementation of the second enclosed volume 52 of the Fig. 7 embodiment of the tank assembly 38. In Fig. 8, the second enclosed volume 52 is provided with a coolant conduit 62 which is in fluid communication with the first cooling line 22 of the cooling system 20. The coolant conduit 62 is only schematically illustrated in Fig. 8, but may be designed to provide an appropriate additional heating in the second enclosed volume. Purely by way of example, the coolant conduit 62 may be wound around the first casing 40. The coolant conduit 62 will increase the rate at which the reactive fluid is heated as compared to the Fig. 7 embodiment and the reactive fluid may also be heated to a temperature higher than what would be obtainable utilizing the Fig. 7 embodiment. However, in order not to obtain too high a temperature of the reactive fluid, the tank assembly 38 may be provided with a control arrangement (not shown) in a manner similar to the one discussed in conjunction with the embodiment illustrated in Fig. 5.

Fig. 9 illustrates still another implementation of the second enclosed volume 52 of the Fig. 7 embodiment of the tank assembly 38. In Fig. 9, the second enclosed volume 52 accommodates a return fuel conduit 64 which comprises a return fuel inlet 66 and return fuel outlet 68, wherein the return fuel inlet 66 is adapted to be in fluid communication with the return fuel line 18 and the return fuel outlet 68 is in fluid communication with the first enclosed volume 42. Thus, rather than heating the reactive fluid by only the fuel 43 in the first enclosed volume 42, the reactive fluid will experience an additional heating by the heat transfer of the return fuel conduit 64. Naturally, the return fuel conduit 64 is preferably made of a material having a high thermal conductivity, such as metal.

Further modifications of the invention within the scope of the appended claims are feasible. For instance, the coolant conduit 62 of the Fig. 8 implementation of the second enclosed volume 52 may be combined with the return fuel conduit 64 of the Fig. 9 implementation in order to obtain a more rapid temperature increase of the reactive fluid in the second enclosed volume 52. Furthermore, although only the conduit system 20 and the exhaust gas treatment system 29 have been used as examples of conduit systems of operation fluids; other conduit systems may of course be feasible. Additionally, a tank assembly 38 according to the present invention may comprise three enclosed volumes wherein the innermost volume is adapted to contain fuel and the two remaining volumes are adapted to contain different operational fluids, such as a coolant and a reactive fluid. Such a tank assembly may be designed as a triple bottom tank or a double bottom tank having a radially extending wall separating the second and third volumes. As such, the present invention should not be considered as limited by the embodiments and figures described herein. Rather, the full scope of the invention should be determined by the appended claims, with reference to the description and drawings.