SE541303C2

SE541303C2 - A method for checking the functionality of a pump in an internal combustion engine system

Info

Publication number: SE541303C2
Application number: SE1751332A
Authority: SE
Inventors: Tommy Albing
Original assignee: Scania Cv Ab
Priority date: 2017-10-27
Filing date: 2017-10-27
Publication date: 2019-06-25
Also published as: WO2019083428A1; SE1751332A1

Abstract

An internal combustion engine system comprises an engine (8) with injectors (6) for injecting fuel into cylinders (7) of the engine and in a fuel feeding system a main fuel tank (1) , a catch tank (3), a first pump (2) configured to pump liquid from the main fuel tank to the catch tank and a further second pump (4) configured to pump fuel from the catch tank to the injectors. The functionality of the first pump is checked while after stopping operation of the first pump start it again and measure how long time it will take to raise the level of fuel in the catch tank to a certain level while running the pump at a fixed number of revolutions per minute and simultaneously measuring the amount of fuel leaving the catch tank by measuring the amount of fuel injected into the cylinders by the injectors (6). The flow out of the first pump is calculated and compared with an ideal value thereof for determining the functionality of the first pump (2).

Description

A method for checking the functionality of a pump in an internal combustion engine system TECHNICAL FIELD OF THE INVENTION AND BACKGROUND ART The present invention relates to a method for checking the functionality of a first pump arranged in a fuel feeding system of an internal combustion engine system, said internal combustion engine system comprising an internal combustion engine with injectors for injecting fuel into cylinders of the combustion engine and in the fuel feeding system a main fuel tank, a catch tank, a said first pump configured to pump liquid fuel from the main fuel tank to the catch tank and a further second pump configured to pump fuel from the catch tank to said injectors, as well as a said internal combustion engine system.

The invention is not restricted to such methods carried out for any particular type of internal combustion engine or fuel, but diesel and ethanol may be mentioned by way of examples. Furthermore, the invention relates to such internal combustion engine systems for any type of use, such as industrial applications, in grinding machines and all types of motor vehicles, although the invention is particularly applicable to utility vehicles, especially wheeled utility vehicles, such as trucks or lorries and buses, which is the reason for in some parts below discussing this use for illuminating the invention but in no way restrict it thereto.

Said first pump is advantageously an electric pump, but it may also be a mechanical pump. The components of the fuel feeding system mentioned above are part of a low pressure part of this system and said second pump will pump fuel to said injectors through a highpressure part of the fuel feeding system. This high-pressure part has nothing to do with the present invention and may have an arbitrary design.

A fuel feeding system with a catch or intermediate tank arranged in the fuel feeding path between the main fuel tank and said highpressure part has a number of advantages. An arrangement of a said catch tank, which normally has a considerably smaller volume than the main fuel tank, is particularly interesting in motor vehicles, which may be wheeled, such as trucks and buses, or for instance running on caterpillar treads, such as different types of construction machines, since such a catch tank makes it possible to drive the vehicle to a position in which less fuel is left in the system than would be the case when only having a main fuel tank, since the vehicle has to then be stopped for refueling before the fuel level in the main fuel tank is that low that a pump connected thereto may not feed fuel out thereof when the motor vehicle is standing on horizontal ground.

The performance of a said first pump, especially when this is an electric pump, may vary due to manufacturing tolerances and aging effects, such as cavitation, wear and others. This makes it beneficial to have some way of estimating the performance/efficiency, i.e. the functionality, of such a first pump online during operation or offline in a workshop, which is what the present invention aims to obtain.

SUMMARY OF THE INVENTION The object of the present invention is to provide a method and a system of the type defined in the introduction solving the problem mentioned above.

This object is with respect to the method obtained by providing such a method with the features listed in appended claim 1.

Thus, by stopping the operation of the first pump thereof and then start the operation while driving the pump at a fixed number of revolutions per minute again and measuring the increase of fuel in the catch tank and how much fuel is leaving the catch tank during a certain period of time the flow out of the pump may be determined. When a value of the flow out of the pump has been obtained this may be compared with an ideal flow out for determining the performance of the pump. This information may then be used to carry out maintenance work, replacement of components of the pump or the entire pump or taking other measures. Said amounts determined by the measurements may be in the form of mass or volumes of fuel.

According to an embodiment of the invention said start of the catch tank is in step c) determined by measuring the amount of fuel injected into the cylinders by the injectors from the time of stopping operation of said first pump in step a) and subtracting this amount from the value of the content of the catch tank measured at the time of stopping the operation of said first pump in step a). This measurement may then be carried out by accumulating the amount of fuel injected in every injection into cylinders of the engine from the time of stopping the operation of the first pump to the time of starting it again. This amount of accumulated fuel is assumed to be known in the engine management system of the internal combustion engine system in question.

According to another embodiment of the invention the amount of fuel leaving the catch tank is in step d) measured by measuring the amount of fuel injected by said injectors into the cylinders as of said starting time. Thus, the amount of fuel leaving the catch tank during said duration is also obtained by measuring the accumulated amount of fuel injected in every injection during the period of time in question. This means that no extra fuel measuring sensor is needed for carrying out said measurements, although it would in principal be possible to have an extra sensor for obtaining this.

According to another embodiment of the invention the content of the catch tank is recorded when the operation of said first pump is stopped in step a) and the value of this content is then in step e) used as said certain stop content. To use the content value obtained when the operation of the pump is stopped as the content value to be obtained after starting the pump again will simplify the method.

According to another embodiment of the invention the content of fuel in the catch tank is measured before the stopping of operation of said pump in step a) and the first pump is operated to obtain a predetermined value of said content to be used as a said stop content in step e) to carry out step a) when this content value is reached. Said predetermined value does then correspond to a certain level of fuel in the catch tank being higher than catch tank fuel levels during normal operation of the internal combustion engine system, so that it will be enough to have one single fuel level sensor in the catch tank reacting upon reaching of this certain level by the fuel in the catch tank for carrying out catch tank fuel content measurements when carrying out the method according to the present invention.

According to another embodiment of the invention the method is carried out on an internal combustion engine system of a motor vehicle, such as a wheeled motor vehicle, especially in the form of a truck or a lorry or a bus.

The object of the present invention is with respect to the internal combustion engine system obtained by providing such a system with the features listed in the characterizing part of the appended claim directed at such a system. The advantages and advantageous features of such a system and the embodiments thereof defined in the dependent claims appear clearly from the above discussion of the method and the embodiments thereof according to the present invention.

The invention also relates to a computer program, a computer readable medium, an electronic control unit and a motor vehicle according to the appended claims directed thereto.

Further advantageous features as well as advantages of the present invention will appear from the description following below.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a specific description of an embodiment of the invention cited as an example.

In the drawings: Fig. 1 is a simplified schematic view showing an internal combustion engine system according to the invention and upon which the method according to the present invention is applicable, Fig. 2 is a flow chart illustrating the steps carried out in a method according to an embodiment of the invention, and Fig. 3 illustrates schematically an electronic control unit according to the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION Fig. 1 illustrates schematically an internal combustion engine system according to an embodiment of the present invention and upon which the method according to the invention is applicable. This system has a fuel feeding system with a main fuel tank 1 and a first pump 2 in the form of an electrical pump acting as a transfer pump pumping fuel from the main fuel tank to a catch tank 3. A second electrical pump 4 (may also be mechanical) is configured to pump fuel from the catch tank further to a high-pressure part 5 of the fuel feeding system having a design being of no importance for the present invention besides containing injectors 6 for injecting fuel into cylinders 7 of an internal combustion engine 8. The combustion engine is arranged in a motor vehicle 9.

A level sensor 10 is arranged to indicate when the level of the fuel 1 1 inside the catch tank reaches a predetermined height which may be at a higher level than catch tank fuel levels during normal operation of the internal combustion engine system, but the level of fuel in the catch tank may just as well under normal operation of the engine be higher than said predetermined level.

A control unit 12 is configured to obtain checking of the functionality of the first pump 2 by controlling the operation of the first pump 2 and the internal combustion engine 8 while receiving information from the level sensor 10 and a member 13 measuring the amount of fuel injected by the injectors 6 into the cylinders of the engine.

A method according to an embodiment of the invention is carried out in the following way. The engine 8 is driven while carrying out the method which may be done during normal driving of the vehicle or offline in a workshop. The different steps of the method are controlled by the control unit 12, and the method is started by controlling the first pump 2 to operate in such a way that the level of the fuel 11 inside the catch tank 3 aligns with the level sensor 10, which will then send information thereabout to the control unit controlling the first pump 2 to stop. The content of fuel in the catch tank is from the time of stopping the operation of the first pump indirectly measured by measuring the amount of fuel leaving the catch tank by accumulating the amount of fuel injected in every injection of the injectors 6 from that moment and subtract this amount from the content corresponding to the fuel level in alignment with the level sensor 10. When a predetermined start content of fuel in the catch tank is reached the first pump 2 is controlled to start and run at a fixed number of revolutions per minute. The time for said starting is recorded by the control unit as a starting time. The control unit does control the member 13 to start measuring the amount of fuel leaving the catch tank as of said starting time by accumulating the amount of fuel injected in every injection carried out by the injectors 6. The first pump 2 is controlled to operate so that the level of the fuel in the catch tank comes into alignment with the level sensor 10 again. The moment when this happens is recorded as a stop time and a duration of the first pump operation is by the control unit determined as the time elapse from said starting time to said stop time. The difference between the start content and the stop content is by the control unit determined as a first amount of fuel, and the control unit determines the amount of fuel injected by the injectors during said duration as a second amount of fuel. The control unit 12 is thereupon calculating the flow out of the first pump as (first amount of fuel second amount of fuel) / duration and compare the value of this flow out calculated with the value of (displacement x number of revolutions per minute) / time, which is the flow out of the pump in an ideal case, to determining the functionality of the pump as the flow out calculated / ideal flow out, which may be called volumetric efficiency of the pump.

Fig. 2 illustrates a flow chart of a method according to an embodiment of the present invention carried out for an internal combustion engine system of the type shown in Fig. 1 for checking the functionality of the first pump thereof. The method is started with a step S1of continuing to drive the engine, which is done when carrying out all further steps of the method. The pump is then in a step S2operated to align the fuel level in the catch tank with the level sensor. When the alignment has been obtained the operation of the pump is in a step S3stopped. In a step S4it is then started to calculate the accumulated amount injected by the injectors, i.e. estimated the amount of fuel leaving the catch tank. In a step S5the question is asked if the accumulated amount has reached a predetermined value m1, and when the answer to this question is yes the operation of the pump is started again while logging time t1in a step S6. A calculation of the accumulated amount injected by injectors is restarted at the time t1in a step S7. In a step Ss the question is asked whether the catch tank fuel level aligns with the level sensor, and when the answer to this question is yes the time is logged as t2and the pumping duration is calculated as the time it took the pump to fill the catch tank back to the level sensor level. The accumulated amount injected by the injectors during t2-tiis determined as m2. In a step S10the flow out of the pump is calculated as (m1+m2)/(t2-t1), whereupon in a final step S11the volumetric efficiency of the pump is calculated as the flow out calculated / (displacement x number of revolutions per minute / t) of the pump.

Computer program code for implementing a method according to the invention is with advantage included in a computer program which can be read into the internal memory of a computer, e.g. the internal memory of an electronic control unit of a motor vehicle. Such a computer program is with advantage provided via a computer program product comprising a data storage medium which can be read by a computer and which has the computer program stored on it. Said data storage medium is for example an optical data storage medium in the form of a CD ROM disc, a DVD disc etc., a magnetic data storage medium in the form of a hard disc, a diskette, a cassette tape etc., or a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type. Fig. 3 illustrates very schematically an electronic control unit 12 comprising an execution means 14, e.g. a central processor unit (CPU), for execution of computer software. The execution means 14 communicates with a memory 15, e.g. of the RAM type, via a data bus 16. The control unit 12 comprises also a non-transitory data storage medium 17, e.g. in the form of a flash memory or a memory of the ROM, PROM, EPROM or EEPROM type. The execution means 14 communicates with the data storage medium 17 via the data bus 16. A computer program comprising computer program code for implementing a method according to the invention, e.g. in accordance with the embodiment illustrated in Fig. 2, is stored on the data storage medium 17.

The invention is of course in no way restricted to the embodiments described above, since many possibilities for modifications thereof are likely to be obvious to one skilled in the art without having to deviate from the scope of invention defined in the appended claims.

Claims

1. A method for checking the functionality of a first pump (2) arranged in a fuel feeding system of an internal combustion engine system, said internal combustion engine system comprising an internal combustion engine (8) with injectors (6) for injecting fuel into cylinders (7) of the combustion engine and in the fuel feeding system, a main fuel tank (1) , a catch tank (3), a said first pump (2) configured to pump liquid fuel from the main fuel tank to the catch tank and a further second pump (4) configured to pump fuel from the catch tank to said injectors, in which said engine (8) is driven while carrying out the method comprising the following steps carried out in the order mentioned: a) stopping operation of said first pump (2), b) measuring the content of fuel in the catch tank (3), c) starting said first pump when a predetermined start content of fuel in the catch tank is reached while running the pump at a fixed number of revolutions per minute and recording the time for said starting as a starting time, d) starting to measure the amount of fuel leaving the catch tank (3) as of said starting time, e) measuring the content of fuel in the catch tank and recording the time when this content has reached a certain stop content as a stop time, f) determining duration of the first pump operation as the time elapsed from said starting time to said stop time, g) determining the difference between said start content and said stop content as a first amount of fuel, h) determining the amount measured in steps d) and e) during said duration from the starting time to the stop time as a second amount of fuel, i) calculating the flow out of the first pump (2) as (first amount of fuel second amount of fuel) / duration, and j) comparing the value of said flow out calculated with the value of (displacement x number of revolutions per minute) / time for said first pump to determine functionality of the pump.

2. A method according to claim 1, characterized in that said start content of the catch tank (3) is in step c) determined by measuring the amount of fuel injected into the cylinders (7) by the injectors (6) from the time of stopping operation of said first pump (2) in step a) and subtracting this amount from the value of the content of the catch tank measured at the time of stopping the operation of said first pump in step a).

3. A method according to claim 1 or 2, characterized in that the amount of fuel leaving the catch tank (3) is in step d) measured by measuring the amount of fuel injected by said injectors (6) into the cylinders (7) as of said starting time.

4. A method according to any of the preceding claims, characterized in that the content of the catch tank (3) is recorded when the operation of said first pump (2) is stopped in step a) and the value of this content is then in step e) used as said certain stop content.

5. A method according to claim 4, characterized in that the content of fuel in the catch tank (3) is measured before the stopping of operation of said first pump (2) in step a) and the first pump is operated to obtain a predetermined value of said content to be used as a said stop content in step e) to carry out step a) when this content value is reached.

6. A method according to any of the preceding claims, characterized in that it is carried out on an internal combustion engine system of a motor vehicle (9), such as a wheeled motor vehicle, especially in the form of a truck or a lorry or a bus.

7. An internal combustion engine system comprising an internal combustion engine (8) with injectors (6) for injecting fuel into cylinders (7) of the combustion engine and a fuel feeding system having a main fuel tank (1) , a catch tank (3), a first pump (2) configured to pump liquid fuel from the main fuel tank to the catch tank and a further second pump (4) configured to pump fuel from the catch tank to said injectors, characterized in that the system further comprises an assembly configured to check the functionality of said first pump, and that said assembly comprises on one hand an arrangement configured to measure the content of fuel in the catch tank and including a member (13) configured to measure the amount of fuel leaving the catch tank and on the other hand a control unit (12) configured to obtain checking of the functionality of said first pump (2) during operation of the combustion engine (8) by consecutively controlling the first pump to stop, the arrangement to measure the content of fuel in the catch tank (3), the first pump to start again and run at a fixed number of revolutions per minute upon information from said arrangement that a predetermined start content of fuel in the catch tank is reached, to record the first pump operation starting time, said member (13) to measure the amount of fuel leaving the catch tank (3) as of said starting time, to record the time when the content in the catch tank has reached a certain stop content as a stop time, to determine duration of the first pump (2) operation as the time elapsed from said staring time to said stop time, to determine the difference between said start content and said stop content as a first amount of fuel, to determine the amount of fuel measured by said member (13) during said duration as a second amount of fuel, to calculate the flow out of the first pump (2) as (first amount of fuel second amount of fuel) / duration and compare the value of said flow out calculated with the value of (displacement x number of revolutions per minute) / time for said first pump to determine the functionality of the pump (2).

8. An internal combustion engine system according to claim 7, characterized in that said member (13) is configured to measure the amount of fuel leaving the catch tank (3) by measuring the amount of fuel injected by the injectors (6) into the cylinders (7) of the engine (8).

9. An internal combustion engine system according to claim 7 or 8, characterized in that said arrangement comprises a further member (10) configured to sense the fuel level in the catch tank (3) and react upon reaching of a certain level by the fuel in the catch tank being higher than catch tank fuel levels during normal operation of the internal combustion engine system, and that the control unit (12) is configured to start said checking by controlling the first pump (2) to operate to reach said certain level by the fuel inside the catch tank (3) and when doing that to control said stopping of the operation of the first pump (2) and after controlling the first pump to start record the time when the content in the catch tank (3) has reached a certain stop content being equal to the content for said reaction by said further member.

10. An internal combustion engine system according to any of claims 7-9, characterized in that said first pump (2) is an electric pump.

11. A computer program comprising instructions which, when the computer program is executed by a computer, cause the computer to carry out the method according to any of claims 1 -6.

12. A computer-readable medium comprising instructions, which, when executed by a computer, cause the computer to carry out the method according to any of claims 1-6.

13. An electronic control unit (12) comprising an execution means (14), a memory (15) connected to the execution means and a data storage medium (17) which is connected to the execution means (14) and on which the computer program code of the computer program according to claim 11 is stored.

14. A motor vehicle, especially a wheeled motor vehicle, in particular a heavy wheeled motor vehicle, such as a truck or a lorry or a bus, characterized in that it is provided with an internal combustion engine system according to any of claims 7-10 and/or an electronic control unit according to claim 13.