WO2014168562A1

WO2014168562A1 - Method and device for detecting disruptions in a fuel system

Info

Publication number: WO2014168562A1
Application number: PCT/SE2014/050424
Authority: WO
Inventors: Dan CEDFORS; Kim KYLSTRÖM
Original assignee: Scania Cv Ab
Priority date: 2013-04-09
Filing date: 2014-04-07
Publication date: 2014-10-16
Also published as: BR112015020744A2; SE1350438A1; SE541143C2; DE112014001034B4; DE112014001034T5

Abstract

A device for the supply of fuel from a fuel tank (1) to a high pressure part (2) of a system for fuel injection in a combustion engine, having at least one electrically operated pump (10) arranged in a conduit between the fuel tank and the high pressure part. Means (17) are arranged to measure the power consumption of the pump, as well as means (18) to measure the engine speed of the pump. A device (16) compares the relationship between the measured power consumption and measured engine speed with stored so-called normal values of this relationship and equates discrepancies exceeding a certain level in this comparison with detection of the occurrence of a leakage, or partial or total stop in the conduit (7).

Description

Method and device for detecting disruptions in a fuel system

FIELD OF THE INVENTION AND BACKGROUND TECHNOLOGY

The present invention pertains to a device for supply of fuel from a fuel tank to a high pressure part of a system for fuel injection in a combustion engine, wherein the device comprises a conduit with a first end connected to the fuel tank and a second end adapted to be connected to a said high pressure part, and at least one pump arranged in said conduit and adapted to supply fuel through this toward the high pressure part, wherein the pump is electrically powered, and a method according to the preamble of the enclosed independent method patent claim.

Thus, the invention is not limited to any certain type of combustion engine or fuel, and diesel and ethanol may be mentioned as a couple of non-limiting examples of fuel. The invention also pertains to supply of fuel to combustion engines adapted for all types of use, such as in industrial applications, crushing machines and in various types of motor vehicles, even though the invention is particularly applicable to wheeled motor vehicles, especially commercial vehicles, such as trucks and buses and will for this reason sometimes be discussed in this application, with the objective of elucidating, but not limiting, the invention.

Further, the invention only pertains to the adaptation of the so- called low pressure part in a system for fuel injection in a com- bustion engine, and the high pressure part and the fuel injection itself to which the low pressure part is connected may have any design. In a device of the type defined above, problems with supply of fuel may arise in the form of leakages or stops in the conduit between the fuel tank and the high pressure part. These problems may take the form of various types of operational disruptions of the engine or equipment connected to the latter, difficulties with engine start, congested starting engines or similar, which may not necessarily be associated with fuel supply problems. It is therefore desirable to discover leakages or stops in said conduit at an early stage in order, depending on the degree thereof, to take suitable measures, such as immediate stop of the combus- tion engine or perhaps a mere registration of the fact that something should be fixed or checked next time the engine is stopped, or that the system needs maintenance. If more serious leakages or stops are not discovered immediately, there is a risk of significant damage, such as in the event of leakages on the pressure side of said pump, which in the event the combustion engine is still in operation, may entail that fuel continues to spray over warm components in the engine space.

Prior art solutions of this type have left a lot to be desired with respect to the possibilities of detecting the occurrence of disruptions in the fuel supply, especially at an early stage, and to identify the type of disruptions in question.

SUMMARY OF THE I NVENTION The objective of the present invention is to provide a method and a device of the type defined above which are improved in at least some respect in relation to prior art devices of this type and prior art methods with respect to handling the above mentioned problem.

This objective is achieved according to the invention, in relation to the method, by providing such a method with the features listed in the characterising portion of patent claim 1 .

The invention thus uses the fact that the at least one pump which is used for fuel supply is electrically driven, which makes it possible, by analysing the latter's function with respect to power consumption and engine speed, to draw conclusions with respect to the occurrence of stops or leakages in the conduit. Thus, in the event of the occurrence of a leakage or a total or partial stop in the conduit, the relationship between the measured power consumption and the measured engine speed will differ from a normal value of this relationship, and by carrying out a corresponding comparison a disruption may be detected. Thus, in the event of an intact fuel supply system, the pump has a certain engine speed at a given power consumption. Thus stops both upstream and downstream of the pump, as well as suction leakages and pressure leakages, may be detected. In the event of minor divergences, the control of the pump may be somewhat modified and the disruption may be corrected at a later maintenance of the system, so that for example in the event of a minor suction leakage, that is to say a leakage upstream of the pump, the pump's engine speed in the event of a given request for fuel supply to the combustion engine may be somewhat increased and thus an operational disruption may be avoided.

According to the invention, the method is carried out in a said low pressure part with two fuel tanks, a first main fuel tank connected via a first section of the conduit to a middle fuel tank, which in turn is connected to said high pressure part via a second section of the conduit, and in the first section of the conduit a so-called transfer pump is arranged to supply fuel from the main fuel tank to the middle fuel tank, and in the second conduit section a so-called supply pump is arranged to supply fuel from the middle fuel tank to said high pressure part. An arrangement of such a middle fuel tank, which normally has a significantly lesser volume than the main fuel tank, is particularly interesting in motor vehicles, which may be wheeled, such as trucks and buses, or for example crawlers, such as different types of construction machines, since this makes it possible to drive the vehicle to a position in which less fuel remains in the system than would be the case with only one main fuel tank, where the vehi- cle must be stopped for fuelling before the fuel level in the main fuel tank is so low that the pump connected thereto is not able to supply fuel from this when the motor vehicle stands on a horizontal base. If there is fuel in the middle fuel tank, however, the vehicle may in such case still be driven, and when the vehicle en- counters a section where the road has an incline, additional fuel may be fed from the main fuel tank to the middle fuel tank in order to continue driving the vehicle. Another advantage of such a fuel supply system is, that when the combustion engine is test driven, it is sufficient to fill the middle fuel tank and thus a sig- nificant amount of fuel may be saved. In addition, many compo- nents that form part of the fuel supply system , for example filters, may be arranged at the middle fuel tank and thus volume may be saved. In such a low pressure part, the power consumption and engine speed may be measured in the feeding pump and/or the transfer pump and compared with expected normal values in order to detect leakages or stops in any of the conduit parts.

According to one embodiment of the invention, the fuel pressure is measured in one position in aid conduit. With such measure- ment of the fuel pressure, information is obtained which may be used to determine the type of disruption, leakage or stop, and on which side, upstream or downstream , of the pump the disruption occurs. According to another embodiment of the invention, the method comprises the step of measuring the level of the fuel in the fuel tank and, in the event of the level information showing the presence of fuel in the tank and a measured engine speed of the pump which, with power consumption measured simultaneously, exceeds the engine speed expected at this power consumption by more than a certain threshold, wherein such threshold may be 5%, 10% or 20%, of confirming that a leakage in said conduit has been detected . By verifying that there really is fuel in the fuel tank, it is possible in this manner to conclude that there is a leakage in the conduit at a noticeably higher engine speed of the pump than expected at a given power consumption of the pump.

According to another embodiment of the invention, the fuel pressure is measured in a position downstream of the pump; when detection of a leak in the conduit is confirmed , the pump is shut off and at the same time the fuel pressure in said position is measured, and a pressure fall in said position, caused by shutting off the pump, is compared to stored values of such a pressure fall in order to conclude whether the detected leak is located in the conduit upstream or downstream of the pump. Said pressure fall will be of different size depending on the position of the leak, and be larger for a given size of the leak if it is located downstream of the pump than if it is located upstream of the pump. The comparison may thus be used to localise the leak.

According to another embodiment of the invention it is determined that, in the event of a result of said comparison that a measured engine speed of the pump with a simultaneous measured power consumption is below the engine speed expected with such power consumption by more than a certain threshold, where this threshold may be 5%, 10% or 20%, an at least partial stop in the conduit is detected. Thus stops in the conduit may be detected by determining that, with a certain power consumption of the pump, the engine speed is noticeably lower than the ex- pected engine speed. Thus, according to a further development of this embodiment, a control of whether fuel arrives to the high pressure part may be carried out, and if the control shows that no fuel reaches the high pressure part, it is determined that a total stop in aid conduit is detected, provided that fuel still remains in the fuel tank.

According to another embodiment of the invention, the fuel pressure is measured in several positions at mutual distances along aid conduit, and the pressure values measured in consecutive positions in the fuel supply direction along the conduit are com- pared with each other, and at a difference between these pressures exceeding a normal pressure difference by at least one predetermined value, such as at least 10% or at least 20% of the expected difference, it is determined that at least a partial stop in said conduit in a position between said both positions has been detected. By measuring the fuel pressure on either sides of a part or component in the fuel supply conduit which risks to be clogged totally or partly, such clogging may be discovered and localised at an early stage. Thus, according to a further devel- opment of this embodiment, the fuel pressure may be measured in two positions on each side of a fuel filter arranged inside the conduit, in order to facilitate the detection of a total or partial stop in said filter. According to one embodiment of the invention, the power consumption and the engine speed of the transfer pump are measured, and the comparison above is carried out in order to detect the occurrence of leakages or stops in said first conduit section. According to a further development of the embodiment mentioned above, the level of the fuel in the middle fuel tank is measured and the measured level of the fuel in the middle fuel tank is taken into consideration, when determining whether the occurrence of leakages or stops in said first conduit section may be deemed to have been detected.

According to another embodiment of the invention, the power consumption and the engine speed of the feeding pump are measured, and the comparison above is carried out in order to determine whether leakages or stops in aid second conduit section may be deemed to have been detected.

According to another embodiment of the invention, an alarm sig- nal is emitted on detection of the occurrence of a leakage or stop in aid conduit. Thus, in for example a combustion engine of a motor vehicle, the driver may obtain information about what has been detected, so that the latter may decide on suitable measures depending on the alarm signal emitted.

The invention also provides a device according to the introduction, which is equipped with the features in the characterising portion of the enclosed independent device patent claims. The advantages of such a device and the embodiments thereof, de- fined in the non-independent device patent claims, are made very clear in the discussion above regarding the method according to the invention.

The invention also pertains to a computer program with the fea- tures listed in patent claim 17, a computer program product with the features listed in patent claim 8, an electronic control device with the features listed in patent claim 19, and a motor vehicle according to patent claim 20. Other advantageous features and advantages regarding the invention are set out in the description below.

BRI EF DESCRIPTION OF THE DRAWINGS Below are descriptions of example embodiments of the invention, with reference to the enclosed drawings, in which:

Fig. 1 is a very schematic view illustrating the structure of a system for fuel supply to a combustion engine, comprising a device according to a first embodiment of the invention,

Fig. 2 is a view in analogy with. 1 , illustrating the structure of a device according to a second embodiment of the inven- tion,

Fig. 3 is a view in analogy with fig. 1 , illustrating a device according to a third embodiment of the invention,

Fig. 4 is a flow chart showing a method according to an embodiment of the invention,

Fig. 5 is a diagram of an electronic control device for the implementation of a method according to the invention,

Fig. 6 shows schematically a motor vehicle according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS ACCORDING TO THE INVENTION

Fig. 1 shows a system for fuel injection in a combustion engine equipped with a device according to a first embodiment of the in- vention for supply of fuel from a fuel tank 1 , which is here divided into two containers, to a high pressure part 2 in the system, whose adaptation is not related to the invention and which begins with a high pressure pump 3, which pumps fuel at a high pressure to a track 4 with nozzles 5 for injection of the fuel into the cylinders of a combustion engine 6, which here is arranged in a motor vehicle 100 (see figure 6). Thus, the fuel pressure in the high pressure part may typically be higher than 2000 bar, while it is in the range of 2-5 bar in a conduit 7 of the device, connected with a first end 8 via a suction filter 30 to the fuel tank 1 and a second end 9 adapted to be connected to the high pressure part 2. The components which are drawn inside the frame M are here arranged on the combustion engine.

The device has a pump 10 arranged inside the conduit 7, adapted to supply fuel from the fuel tank 1 to the high pressure part 2 in the conduit, and an electric engine 1 1 which operates the pump, and this may here be controlled independently of the control of the combustion engine by a control device which is not displayed here. Downstream of the pump a so-called pre- pressure filter 12 is arranged and connected to a container 1 3 for water separated from the fuel . Further downstream in the conduit a fuel filter 14 is arranged for filtration of the fuel before it reaches the high pressure pump 3. The device also comprises an element 1 5 adapted to measure the level of the fuel in the fuel tank 1 and to send information about this level to a device 16. The first and second means 1 7 and 18, respectively, are adapted to measure the power consumption of the pump and its engine speed , and to send informa- tion thereof to the device 16. The elements 19, 20 are arranged to measure the fuel pressure in the conduit 7 downstream of the pump, as well as upstream and downstream, respectively, of the fuel filter 14, and to send information about this to the device 16. Further, a control system 21 in the combustion engine communi- cates with the device 16, such as to notify the latter of whether fuel is arriving to the high pressure part. The device in turn communicates with an alarm element 22.

The function of the device according to the invention is as fol- lows. During operation of the combustion engine, said device 16 is equipped with measuring values from the above mentioned element and means 15, 17-20 and system 21 , and it is adapted to compare the relationship between measured power consumption and measured engine speed of the pump with stored so- called normal values of this relationship, and in the event of a discrepancy in comparison being larger than a predetermined threshold value, to equate with this with a detection of the occurrence of a leakage or partial or total stop in the conduit 7. The size of the detected leakage or stop determined by the device decides whether the device will notify this to the alarm element 22, merely store the information thereof for future maintenance, use the result for changing the control of any component in the fuel supply system, such as the pump 10, or ensure that the combustion engine is immediately turned off.

If a leakage occurs in the conduit 7, this will entail that the engine speed of the pump 10 is higher than what may be expected considering the power consumption of the pump, while the reverse relationship will prevail in the occurrence of a partial or to- tal stop in the conduit, so that the device may differentiate between these two types of disruptions.

A so-called suction leakage, that is to say a leakage in the conduit upstream of the pump 10, is normally very difficult to detect visually, but may be discovered in this manner, so that potential operational disruptions in the fuel supply system, starting engines or similar may be connected with such a leak. By investigating how quickly the fuel pressure in the conduit 7 is falling at the position for the pressure measurement element 19 when the pump is turned off, it may be determined whether the detected leak is a suction leak or a pressure leak, since the pressure falls significantly more rapidly in the latter case.

It may also be determined in which part of the device 16 a partial or total stop in the conduit 7 is located, by analysing the information from the pressure measuring elements 19, 20 during the operation of the pump 10 and in combination with turning the pump off (this may be carried out via element 41 ). In the event of a difference between pressures measured by the elements 19 and 20 over a specific level, it may be concluded that the fuel filter 14 is at least partly clogged.

Fig. 2 illustrates a device according to a second embodiment of the invention, and those parts in this embodiment which are also used in the first embodiment are equipped with the same reference numerals and will not be explained again here. This device differs from the device according to the first embodiment since, in addition to a first main fuel tank 1 , it comprises a middle fuel tank 23, which is connected to the main fuel tank via a first sec- tion 24 of the conduit 7. The middle fuel tank is in turn connected to the high pressure part 2 via a second part 25 of the conduit. In the first conduit section a so-called transfer pump 26 is arranged to supply fuel from the main fuel tank to the middle fuel tank, and in the second conduit section a so-called feeding pump 27 is ar- ranged to supply fuel from the middle fuel tank to the high pres- sure part. Both the pumps are operated by electric engines 1 1 , 1 1 '. By way of example, the main fuel tank 1 has a volume of 1 000 litres, while the middle fuel tank has a volume of 20 litres. The feeding pump 27 is here arranged in the middle fuel tank, which is also equipped with a fuel level detector 40 adapted to send information regarding the filling level of this tank to the device 16.

Everything marked to be inside of the frame 28 is arranged as one unit together with the middle fuel tank 23, so that the transfer pump 26 is arranged to supply fuel in the first conduit section 24 mainly by sucking fuel from the main fuel tank 1 .

By measuring the power consumption and engine speed of the transfer pump 26, the device 16 may detect suction leaks in the first conduit section 24, or total or partial stops therein, such as potentially in the suction filter 30, which may occur in the form of paraffination at lower temperatures where diesel is used as a fuel. In the event of an application on a motor vehicle, the alarm element 22 is adapted to notify the driver if a total stop occurs in the first conduit section, so that he or she knows that they may continue to drive only until the middle tank is empty. The detector 40 may thus notify the driver about how much fuel is available for this purpose.

At the same time clogging of the fuel filter 14 may be detected through analysis of the measuring result from the pressure measuring elements 19, 20. Fig . 3 illustrates a device which differs from the one in fig . 2 since both the pumps are moved here; specifically the transfer pump 26 is moved to be arranged in the first condu it section 24 at a distance from the middle fuel tank 23, and the feeding pump 27 is arranged in the second conduit section downstream of the middle fuel tank.

Here both the pumps are equipped with first means 1 7, 1 7' and second means 1 8, 1 8', respectively, for the measurement of power consumption and engine speed, respectively, and sending of information in this regard to the device 1 6. in order to faci litate detection of the occurrence of a leakage or partial or total stop in the first conduit section 24 as well as in the second conduit section 25.

It also displays how a pressure measurement element 31 is arranged in the first conduit section downstream of the transfer pump 26 , in order to facilitate the determination of whether a detected leakage or stop in this conduit is located upstream or downstream of the transfer pump.

Fig . 4 shows a flow chart illustrating a method according to one embodiment of the invention , for the detection of a disru ption in the form of a leakage or at least a partial stop in a low pressure part of a system for fuel injection in a combustion engine. The method may be carried out with a device of the type illustrated in fig . 1 -3. I n a first step Si the instantaneous power consumption I of a pump arranged in the conduit between the fuel tank and the hig h pressure part is measured , and simultaneously the instanta- neous engine speed of the pump is measured in a second step S₂. In a step S₃ the measured engine speed V is then compared to the engine speed V_f which is expected, according to a normal value, with the measured power consumption I of the pump. In a subsequent step S₄ it is then determined whether the measured engine speed differs by more than a threshold G, e.g. 5%, from the expected engine speed. If the answer to this question is yes, then in step S₅ it is investigated whether the measured engine speed is greater than the expected engine speed. If the answer to this question is yes, it is determined in step S₆ that there is a leakage in the conduit, and if the answer to the question is no, it is determined in step S₇ that there is a partial or total stop or clogging in said conduit. This method is repeated continuously or intermittently as long as the combustion engine is in operation. The information from steps S₆ and S₇ is sent to a step S₈ for po- tential emitting of an alarm. This method may be carried out during normal operation of the combustion engine or during maintenance of the same, or of a motor vehicle, if the engine is arranged in such vehicle. A computer program code for the implementation of a method according to the invention is suitably included in a computer program, loadable into the internal memory of a computer, such as the internal memory of an electronic control device of a combustion engine. Such a computer program is suitably provided via a computer program product, comprising a data storage medium readable by an electronic control device, the data storage medium having the computer program stored thereon. Said data storage medium is e.g. an optical data storage medium in the form of a CD-ROM , a DVD, etc., a magnetic data storage medium in the form of a hard disk drive, a floppy disc, a cassette, etc. , or a Flash memory or a ROM , PROM , EPROM or EEPROM type memory.

Fig. 5 illustrates very schematically an electronic control device 32, comprising execution means 33, such as a central processor unit (CPU), for the execution of computer software. The execution means 33 communicates with a memory 34, e.g. a RAM memory, via a data bus 35. The control device 32 also comprises a data storage medium 36, e.g. in the form of a Flash memory or a ROM, PROM, EPROM or EEPROM type memory. The execution means 33 communicates with the data storage means 36 via the data bus 35. A computer program comprising computer program code for the implementation of a method according to the invention, for example in accordance with the embodiment illus- trated in fig. 4, is stored on the data storage medium 36.

The invention is obviously not limited in any way to the embodiments described above, but numerous possible modifications thereof should be obvious to a person skilled in the area, without such person departing from the spirit of the invention as defined by the appended patent claims.

Measurement and comparison of power consumption and engine speed shall be interpreted broadly herein and also comprise indi- rect measurement of these values. An example of this is that the volume of fuel in the middle fuel tank is measured and how the changes in this are compared with the simultaneously measured power consumption of the transfer pump. If for example said volume is constant, but a much greater power consumption than ex- pected is required by the transfer pump in order to achieve this at a certain fuel consumption of the combustion engine, then there is a leakage or stop in the first conduit section. I n this case, the transfer pump's engine speed is, obviously, also not as may be expected in relation to the measured power consumption .

Claims

Patent claims

Method for the detection of disruptions in the form of leakages or at least partial stops in a low pressure part of a system for fuel injection in a combustion engine (4), wherein the low pressure part comprises a conduit (7) between a main fuel tank ( 1 ) and a high pressure part (2) of the system and at least one electrically operated pump (26, 27), arranged in the conduit for the supply of fuel therein to the high pressure part, wherein said main fuel tank ( 1 ) is connected via a first part (24) of the conduit to a middle fuel tank (23), which in turn is connected to said high pressure part (2) via a second part (25) of the conduit, and wherein a so-called transfer pump (26) is arranged in the first conduit section to supply fuel from the main fuel tank (1 ) to the middle fuel tank (23), and in the second conduit section a so-called feeding pump (27) is arranged to supply fuel from the middle fuel tank (23) to said high pressure part (2),

characterised in that it comprises the following steps:

- measurement of the transfer pump's (26) power consumption,

- measurement of the transfer pump's engine speed,

- comparison of the value of the relationship between the measured engine speed and the measured power consumption with an expected normal value of this relationship for the measured power consumption or engine speed , and

- determination that a mentioned disruption has been detected in the event of a discrepancy between the value arrived at via the measurements of said relationship and said expected normal value, which exceeds a predetermined threshold level .

Method according to claim 1 , characterised in that it comprises the following step:

measurement of the fuel pressure at a position in said conduit (7).

Method according to claim 1 or 2, characterised in that it comprises the following step:

measurement of the level of fuel in the main fuel tank ( 1 ), and that it is determined that a leakage in said conduit (7) is detected in connection with the measurement of the presence of fuel in the fuel tank (1 ) and in the event of a comparison result that the measured engine speed of the transfer pump (26), given the simultaneously measured power consumption, exceeds the expected engine speed for this power consumption by more than a threshold value G , wherein this threshold value is 5%, 10% or 20%.

Method according to claim 2, or claim 2 and 3, characterised in that it comprises measurement of the fuel pressure in a position downstream of the transfer pump (26), and that the method comprises the additional steps:

- in connection with determination of detection of a leakage in said conduit (7), turning off of the transfer pump (26) and simultaneous measurement of the fuel pressure in said position, and

comparison of a pressure fall in said position, caused by the transfer pump being turned off, with stored values of such a pressure fall, in order to determine whether the detected leak is located in the conduit upstream or downstream of the transfer pump.

Method according to any of the previous claims, characterised in that, where the comparison of the value of the relationship between the measured engine speed and the measured power consumption shows a measured engine speed at a measured power consumption which is below the expected engine speed at this power consumption by more than a threshold value G, where this threshold value is 5%, 10% or 20%, it is determined that at least a partial stop has been detected in the conduit (7).

Method according to claim 5, characterised in that it also comprises control of whether the fuel arrives to said high pressure part (2), and that it is determined that a total stop in said conduit (7) is detected if the control shows that no fuel arrives to the high pressure part.

Method according to claim 2, characterised in that measurement of fuel pressure is carried out in several positions spaced along said conduit (7), and that the method comprises the additional step of

comparison of the pressure values measured in consecutive positions in the fuel feeding direction along the conduit, and that it is determined that an at least partial stop in said conduit is detected in a position between said both positions given a difference between the compared pressures exceeding a normal pressure difference by at least one predetermined value, such as at least 10% or at least 20% of the expected difference.

Method according to claim 7, characterised in that measurement of the fuel pressure is carried out in two positions on each side of a fuel filter ( 14) arranged in the conduit, in order to facilitate detection of total or partial stops in this filter.

Method according to any of the previous claims, characterised in that the comparison and determination are carried out in order to detect the occurrence of leakages or stops in said first conduit section (24). 10. Method according to any of the previous claims, characterised in that it also comprises the following step:

measurement of the level of fuel in the middle fuel tank (23), and that said determination is carried out while taking into consideration the measured level of fuel in the middle fuel tank when determining whether a leakage or stop in said first conduit section (24) may be deemed to have been detected.

Method according to any of the previous claims, characterised in that the feeding pump's (27) power consumption and engine speed are measured , and that the comparison and determination are carried out in order to detect the occurrence of leakages or stops in said second conduit section (25). Method according to any of the previous claims, characterised in that it also comprises the following step:

sending of an alarm signal when it is determined that a leakage or stop in said conduit (7) has been detected.

13. Device for supply of fuel from a main fuel tank ( 1 ) to a high pressure part (2) of a system for fuel injection in a combustion engine (6), wherein the device comprises a conduit (7) with a first end (8) connected to the main fuel tank and a second end (9) adapted to be connected to a said high pressure part, and at least one pump (26, 27), arranged in said conduit and adapted to supply fuel therein toward the high pressure part, wherein said first main fuel tank (1 ) is connected via a first section (24) of the conduit to a middle fuel tank (23), which in turn is connected to said high pressure part (2) via a second section (25) of the conduit, and wherein a so-called transfer pump (26) is arranged in the first conduit section to supply fuel from the main fuel tank ( 1 ) to the middle fuel tank (23) and in the second conduit section a so- called feeding pump (27) is arranged to supply fuel from the middle fuel tank (23) to said high pressure part (2), wherein at least the transfer pump is electrically operated,

characterised in that the device also comprises first means (17, 1 7') adapted to measure the power consumption of the transfer pump, second means ( 1 8, 18') adapted to measure the transfer pump's engine speed and a device ( 16) adapted to receive information from said first and second means and to compare the relationship between the measured power consumption and measured engine speed with stored so- called normal values for this relationship, and in the event of discrepancies in said comparison greater than a predetermined threshold level , to equate this with a detection of the occurrence of a leakage or partial or total stop in said conduit.

Device according to claim 13, characterised in that it comprises at least two pressure measurement elements ( 1 9, 20), adapted to measure the fuel pressure in id conduit (7) and arranged to be spaced along the conduit

Device according to claim 14, characterised in that two of said pressure measurement elements ( 1 9, 20) are arranged on each side of a fuel filter ( 14) arranged in the conduit, in order to enable the device to detect total or partial stops in said filter.

Device according to any of claims 1 3-15, characterised in that it comprises a sensor (40) arranged in the middle fuel tank (23), adapted to measure the level of fuel in this fuel tank and to send information thereof to the device (16).

A computer program comprising a program code which, when said program code is executed in a computer, achieves that said computer carries out the method according to any of the claims 1 -12.

A computer program product comprising a data storage medium which is readable by a computer, the computer program code of a computer program according to claim 17 being stored on the data storage medium. Electronic control device (32) in the fuel supply system , comprising an execution means (33), a memory (34) connected to the execution means and a data storage medium (36) connected to the execution means, the computer program code in a computer program according to claim 1 7 being stored on said data storage medium.

20. Motor vehicle ( 100), especially a wheeled motor vehicle, in particular a truck or a bus, characterised in that it comprises a device according to any of claims 1 3-16.