WO2014168563A1

WO2014168563A1 - Method and device for functional check of fuel supply conduit

Info

Publication number: WO2014168563A1
Application number: PCT/SE2014/050425
Authority: WO
Inventors: Dan CEDFORS
Original assignee: Scania Cv Ab
Priority date: 2013-04-09
Filing date: 2014-04-07
Publication date: 2014-10-16
Also published as: SE537030C2; DE112014001055T5; DE112014001055B4; SE1350439A1

Abstract

A 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, comprising a middle fuel tank (12) connected via a conduit to the main fuel tank and via another conduit to the high pressure part. A transfer pump (14) is adapted to supply fuel from the main fuel tank to the middle fuel tank and a feeding pump (17) to supply fuel from the middle fuel tank to the high pressure part. The supply direction of the transfer pump (14) is reversible, and the device has a unit (24) adapted to determine whether a predetermined condition regarding the operation of the combustion engine is met, and if so, to control the transfer pump to temporarily supply fuel from the middle fuel tank (12) toward the main fuel tank (1).

Description

METHOD AND DEVICE FOR FUNCTIONAL CHECK OF FUEL SUPPLY

CONDUIT

The present invention pertains to a device for the supply of fuel from a main fuel tank to a high pressure part of a system for fuel injection in a combustion engine, wherein the device comprises a middle fuel tank connected via a first section of the conduit to the main fuel tank and via a second section of the conduit to said high pressure part, a so-called transfer pump arranged in the first conduit section, adapted to supply fuel from the main fuel tank to the middle fuel tank and a feeding pump arranged in the second conduit section, adapted to supply fuel from the middle fuel tank to said high pressure part, and a method according to the preamble of the enclosed independent method patent claims.

Thus, the invention is not limited to any specific 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 intended 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.

RECORD COPY TRANSLATION

(Rule 12.4) Further, the invention pertains only to the adaptation of the so- called low pressure part in a system for fuel injection in a combustion engine, and the high pressure part and the fuel injection itself to which the low pressure part is connected may have any design.

A device of this type with an arrangement of a middle fuel tank in the fuel supply path between the main fuel tank and said high pressure part has a number of advantages. 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 vehicle 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 encounters a section where the road has an incline, additional fuel may be supplied from the main fuel tank to the middle fuel tank in order to continue driving of 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 significant amount of fuel may be saved. Additionally, any components comprised in the fuel supply system, e.g. filters, may be arranged at the middle fuel tank, and thus volume may be saved. In a device of the type identified above, problems with the supply of fuel in the form of leakages or stops may arise in the supply between the main fuel tank and the high pressure part, and the present invention is mainly focused on the consideration of problems with leakages or stops in the first conduit section between the main fuel tank and the middle fuel tank. These problems may take the shape of various forms of operational disruptions in the combustion engine and equipment connected thereto, which are not always automatically associated with fuel supply problems. It may be particularly difficult to detect suction leaks, i.e. leakages in the first conduit section upstream of the transfer pump. The same applies to clogged fuel armature, i.e. clogging of parts, such as suction filters, at the bottom of a main fuel tank, which, e.g. with the use of diesel as fuel and low temperatures in the fuel tank's environment, may be caused by paraffination of the fuel. To date it has been difficult to detect early incipient problems with suction leaks and clogging, and when such problems are eventually detected, attempts have been made to remedy them through random dismantling of parts of the device and purging thereof with e.g. compressed air.

SUMMARY OF THE INVENTION The objective of the present invention is to provide a device and a method of the type defined above, which facilitate the handling of the above mentioned problems in a better manner than in prior art devices and methods. 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 . By using a transfer pump with a reversible supply direction and by reversing the supply direction of the transfer pump when a predetermined condition regarding the operation of the combustion engine is met, it becomes possible via such reversed supply of fuel from the middle fuel tank toward the main fuel tank, visually to detect whether fuel is leaking into the conduit between the main fuel tank and the transfer pump, i.e. whether there is a suction leak. It will then also be possible to detect the location of the leak. Additionally, such reversed supply of the fuel may be used to "purge" the suction side of the transfer pump and to eliminate total or partial clogging or stops in the latter, such as e.g. clogging of a said suction strainer at the bottom of the main fuel tank by paraffination of diesel in the event of cold weather, e.g. where the combustion engine is arranged in a motor vehicle such as a truck or bus.

According to one embodiment of the invention, it is determined that said condition is met when the combustion engine is started. Thus, when the combustion engine is started, the state of the part of the fuel supply device upstream of the transfer pump may be checked, and potential faults may be detected. At the same time, a "purging" of the transfer pump's suction side may thus occur.

According to another embodiment of the invention, it is determined that said condition is met at predetermined time intervals during the engine's operation. Thanks to the existence of the middle fuel tank, fuel may be supplied via said feeding pump to the combustion engine during the operation of the latter, even if the transfer pump's supply direction is reversed in the short term, and this is used in order to carry out functional checks of the transfer pump's suction side during the engine's operation. Where a combustion engine is arranged in a motor vehicle and diesel is used as fuel, when driving in cold weather the suction filter in the main fuel tank may regularly be hosed clean to prevent that paraffin clogs it, without the driver having to take any initiatives to achieve this, and even without taking any notice of this while driving. At the same time, unwanted stops of the vehicle and time loss due to clogging may be avoided. According to another embodiment of the invention, the method comprises a step of measuring a temperature indicative of the temperature in the region of the main fuel tank, and it is determined that said condition is met at predetermined time intervals during the engine's operation, as long as said temperature is below a predetermined temperature. Thus, problems with potential clogging caused by the fuel being exposed to low temperatures are taken into consideration, such as said paraffination in the event diesel is used as fuel, where the risk of clogging and stops is really impending.

According to another embodiment of the invention, it is determined that said condition is met at maintenance of said system. Thus, at such maintenance, the transfer pump may be operated to supply fuel from the middle fuel tank to the main fuel tank and thus in particular potential suction leaks may be detected.

According to the invention, the method is carried out regarding a conduit connected to an electrically operated transfer pump, and the power consumption of the transfer pump is measured, the engine speed of the transfer pump is measured and the relationship between the measured power consumption and the measured engine speed is compared with stored so-called normal values of this relationship, and it is determined that said condition is met in the event of discrepancies during this comparison exceeding a predetermined threshold level. Here, the fact that the transfer pump is electrically operated is used, making it possible via the analysis of the latter's function in relation to power consumption and engine speed to draw conclusions, with respect to the occurrence of stops or leakages in the conduit between the main fuel tank and the middle fuel tank. 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 the pump has, assuming an intact system for fuel supply between the main fuel tank and the middle fuel tank, a certain engine speed at a given power consumption. Therefore it is suitable to consider that said conditions are met where said discrepancy arises during the comparison.

According to one embodiment of the invention, the level of fuel in the main fuel tank is measured, and in the event of a measured occurrence of fuel in the main fuel tank and a measured engine speed of the transfer pump which, with a simultaneously measured power consumption, differs from the engine speed expected with this power consumption by more than a threshold value, which may be 5%, 10% or 20%, it is determined that said condition is met. By checking that there really is fuel in the fuel tank, it is thus possible to conclude that the difference from said normal value really is attributable to the occurrence of a leakage or a stop and thus said condition may be deemed to be met, and it may be suitable to reverse the supply direction of the transfer pump.

The invention also provides a device, which is equipped with the features in the characterising portion of the enclosed independent device patent claims. The advantages of such a device 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 features listed in patent claim 9, a computer program product with the features listed in patent claim 10, an electronic control device with the features listed in patent claim 1 1 , and a motor vehicle according to patent claim 12. Other advantageous features and advantages regarding the invention are set out in the description below. BRI EF DESCRI PTION OF THE DRAWI NGS

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 one embodiment of the invention,

Fig 2 is a flow chart showing a method according to one embodiment of the invention , is a diagram of an electronic control device for the implementation of a method according to the invention,

Fig . 4 shows a schematic view of a vehicle according to the invention.

DETAI LED DESCRI PTION OF ONE EMBODI MENT ACCORD I NG TO THE I NVENTION

Fig. 1 shows a system for fuel injection in a combustion engine equipped with a device according to one embodiment of the invention for the supply of fuel from a fuel tank 1 , which here is divided into two containers, to a high pressure part 2 of the system, whose adaptation is not at all related to the invention and which begins with a high pressure pump 3, which pumps fuel with a high pressure to a track 4 with nozzles 5 for the injection of fuel into the cylinders of a combustion engine 6, which here is arranged in a motor vehicle 100 (see figure 4). Thus, the fuel pressure in the high pressure part may typically be above 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 9, located near the bottom of the fuel tank, to the main fuel tank and a second end 10 adapted to be connected to the high pressure part 2.

The conduit 7 is divided into two sections, a first section 1 1 which connects the main fuel tank to a middle fuel tank 12, and in which a transfer pump 14 operated by an electric engine 13 is arranged to supply fuel from the main fuel tank to the middle fuel tank. The middle fuel tank 12 is connected to the high pressure part 2 via a second part 15 of the conduit 7. A feeding pump 17 operated by an electric engine 16 is arranged in the middle fuel tank, to supply fuel from the latter to the high pressure part 2 for injection thereof in the combustion engine. The middle fuel tank normally has a volume which is only a fraction of the main fuel tank's volume, such as at the combustion engine of a truck, e.g. 20 I compared to 1000 I in the main fuel tank.

The system also comprises: a pre-pressure filter 18 arranged downstream of the transfer pump and connected to a container 19 for water separated from the fuel. A sensor 20 is adapted to measure the level of the fuel in the middle fuel tank. A fuel filter 21 is arranged in the second conduit section 15 for filtration of the fuel before it reaches the high pressure pump 3, and elements 22, 23 are arranged to measure the fuel pressure in the conduit on each side of the fuel filter 21 , to detect potential clogging thereof. The device comprises one unit 24, adapted to determine whether a predetermined condition regarding the operation of the combustion engine is met, and if so, to control the transfer pump 14 via control of the engine 13 to temporarily supply fuel from the middle fuel tank 12 toward the main fuel tank 1 . First means 25 are adapted to measure the power consumption of the transfer pump and second means 26 are adapted to measure the engine speed of the transfer pump, and these means send information about these values to a device 27, adapted to compare the relationship between the measured power consumption and the measured engine speed with stored so-called normal values of this relationship, and to send the result of this comparison to the unit 24. The unit 24 also obtains information about the combustion engine's operation from a control system 28 of the combustion engine.

Further, an element 29 is arranged to deliver a value for the temperature in the region of the main fuel tank to the unit 24 and an element 30, which is adapted to measure the level of fuel in the main fuel tank 1 and to send information about this level to the unit 24. It is also displayed how the unit 24 may be connected to some type of alarm element 31 , in order to send an alarm if the device should be in such a state that this is deemed justified. Everything marked within the frame M in Fig 1 is arranged on the combustion engine, while the frame 40 marks such items which are connected in the same unit as the middle fuel tank. This means that the transfer pump 14 is located directly at the middle fuel tank, and therefore supplies fuel from the main fuel tank to the middle fuel tank basically only by way of suction, and the first conduit section 1 1 is located upstream of the transfer pump.

The function of the device according to the invention is as follows. When the combustion engine is started, the transfer pump 14 may temporarily, such as for a few seconds, via the unit 24, be controlled by the unit 24 to supply fuel from the middle fuel tank 12 toward the main fuel tank, in order to check the function of the conduit upstream of the transfer pump and potentially to "purge" the latter. When the combustion engine is in operation, the unit may, at predetermined time intervals, control the transfer pump to supply fuel temporarily, such as for 1 -5 seconds, from the middle fuel tank to the main fuel tank. The same applies in the event the device 24 obtains information from the temperature sensor 29 that the temperature is below a predetermined level and that there is therefore a risk of clogging, e.g. paraffination, in the event diesel is used as fuel.

The means 25, 26 measure, during the operation of the combustion engine, the power consumption and the engine speed, respectively, of the pump 14, and when at said comparison of these values with normal values in the device 27, discrepancies are determined, the unit 24 also controls the transfer pump 14 to temporarily supply fuel from the middle fuel tank toward the main fuel tank and/or to send an alarm via the alarm element 31 in the event of significant such discrepancies.

During maintenance of the combustion engine, the transfer pump may also be controlled to supply fuel between the middle fuel tank and the main fuel tank in order to facilitate a visual detection of potentially occurring suction leaks in the first conduit section 1 1 .

Fig 2 shows a flow chart which illustrates a method according to one embodiment of the invention, for functional control of a conduit between a transfer pump and a main fuel tank in a device of the type described above. In a first step Si the combustion engine is driven and fuel is fed via the transfer pump from the main fuel tank to the middle fuel tank. In a second step S₂ it is determined whether a condition for the reversal of the transfer pump's supply direction is met, and if this is the case, step S₃ follows, in which the supply direction of the transfer pump is temporarily reversed, following which step Si resumes. This method may be continuously or intermittently repeated as long as the combustion engine is in operation.

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 . 3 illustrates very schematically an electronic control device 32 comprising execution means 33, such as a central processor unit (CPU), for the execution of a 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 illustrated at Fig 2, is stored in 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.

The transfer pump could be arranged closer to the main fuel tank, even if it most often is advantageous to have it directly at the middle fuel tank. The feeding pump could be located at the combustion engine and suck fuel to the latter from the middle fuel tank.

Claims

Patent claims

Method for functional check of a conduit between an electrically operated transfer pump ( 14) and a main fuel tank (1 ) in a device for the supply of fuel from the main fuel tank to a high pressure part (2) of a system for fuel injection in a combustion engine (6), wherein the device comprises a middle fuel tank ( 12) for receipt of fuel supplied by the transfer pump from the main fuel tank and a feeding pump (1 7) adapted to feed fuel from the middle fuel tank to said high pressure part,

characterised in that it comprises the following steps:

determination of whether a predetermined condition regarding the combustion engine's operation is met, measurement of the power consumption of the transfer pump ( 14),

measurement of the transfer pump's engine speed,

comparison of the relationship between the measured power consumption and the measured engine speed with stored normal values for this relationship, and

determination of said condition being met being made in the event the comparison of the relationship between the measured power consumption and measured engine speed results in a greater discrepancy between the compared values of this relationship than a predetermined threshold, and

reversal of the transfer pump's ( 14) supply direction for temporary supply of fuel from the middle fuel tank (12) toward the main fuel tank ( 1 ) if said condition is met. Method according to claim 1 , characterised in that it is determined that said condition is met when the combustion engine is started .

Method according to claim 1 or 2, characterised in that it is determined that said condition is met at predetermined time intervals during the operation of the combustion engine.

Method according to claim 3, characterised in that it also comprises measurement of a temperature indicative of the temperature in the region of the main fuel tank, and that it is determined that said condition is met at predetermined time intervals during the operation of the engine, as long as said temperature is lower than a predetermined temperature.

Method according to any of the previous claims, characterised in that it is determined that said condition is met during the maintenance of said system .

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 main fuel tank ( 1 ), and that it is determined that said condition is met in the event of a measured occurrence of fuel in the main fuel tank and a measured engine speed of the transfer pump ( 14) which , at a simultaneously measured power consumption of the latter, differs from the engine speed expected with such power consumption , by more than a threshold value. Method according to claim 6 characterised in that the threshold value is 5%, 1 0% or 20%.

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 middle fuel tank ( 12) connected via a first section ( 1 1 ) of the conduit to the main fuel tank and via a second section ( 1 5) of the conduit to said high pressure part, an electrically operated transfer pump ( 14) arranged in the first conduit section, adapted to supply fuel from the main fuel tank to the middle fuel tank and a feeding pump (1 7) arranged in the second conduit section, adapted to supply fuel from the middle fuel tank to said high pressure part,

characterised in that the supply direction of the transfer pump ( 14) is reversible, that the device comprises a unit (24) adapted to determine whether a predetermined condition regarding the operation of the combustion engine is met, and that it comprises first means (25) adapted to measure the power consumption of the transfer pump ( 14), second means (26) adapted to measure the engine speed of the transfer pump and a device (27) adapted to receive information from said first and second means and to compare the relationship between the measured power consumption and the measured engine speed with stored so-called normal values of this relationship and to send the result of this comparison to the unit, and that the unit (24) is adapted to determine that said condition is met in the event of discrepancies in said comparison greater than a predetermined threshold level, and if so to control the transfer pump to temporarily supply fuel from the middle fuel tank ( 12) toward the main fuel tank ( 1 ).

9. 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 -7.

10. 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 9 being stored on the data storage medium .

1 1 . Electronic control device (32) in a 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 9 being stored on said data storage medium.

12. Motor vehicle (100), especially a wheeled motor vehicle, in particular a truck or a bus, characterised in that it comprises a device according to claim 8.