EP2507499B1 - Method for operating a fuel system and device for modifying a pressure in a fuel system - Google Patents

Description

The invention relates to a method for operating a fuel system of a vehicle with electric drive, in which a pressure within a fuel tank of the fuel system can change situation-related.

In addition, the invention relates to an apparatus for varying a pressure in a fuel system comprising substantially a fuel tank for storing fuel on an electric vehicle, a fuel filling device for filling fuel in the fuel tank, and a filter device for filtering fuel gases.

For example, it is from the document DE 10 2006 034 076 A1 known, for a tank leak diagnosis in a tank ventilation device, consisting essentially of a fuel tank, a memory for fuel vapors and an opening into an intake manifold of an internal combustion engine of a vehicle tank vent valve, the memory having a vent line with a shut-off immediately after stopping the engine, a negative pressure in the tank ventilation device by closing the shut-off valve and opening the tank venting valve to subsequently detect a vacuum reduction with the tank venting valve closed at predetermined times, whereby a tank leak diagnosis can be performed in the tank venting device.

US Pat. No. 7,448,367 B1 shows a hybrid vehicle with a fuel vapor retention system, which is operated via a control module, wherein the control module compares fuel temperatures and fuel tank pressures with each other. It is therefore a method apparently how these values can be used to calculate a vapor pressure value by measuring the fuel tank pressure via a sensor.

US 2007/267232 A1 describes a diagnostic control device for fault diagnosis for a hybrid vehicle having an internal combustion engine and an electric motor coupled thereto. The resulting in a fuel tank fuel gas is passed via a degassing line to a canister for treatment or purification of the gas. The internal combustion engine is connected via an inlet pipe with a venting or purge line, which in turn is connected to the canister. Thus, with the valve open, ambient air may be introduced into the canister to clean it, for example, and then to supply the gas together with the air via the line to the engine with the bleed control valve open.

US 2008/271718 A1 describes a method for controlling the fuel gas in a hybrid vehicle. The fuel gas from a fuel tank is channeled into a fuel canister, filtered and discharged into the atmosphere. To prevent saturation, the fuel canister must be purged. The fuel gas is supplied to the internal combustion engine. If the hybrid vehicle is in electrical mode, the internal combustion engine must be started for the flushing process. In order to select the time when the flushing process should start as efficiently as possible, the time is calculated using various parameters.

US 2003 079533 A1 describes an evaporative emission leakage detection system and a leak detection method of an evaporative emission space of a fuel system of a vehicle. To perform a leak test, a differential between the pressure in the evaporative emission space and the ambient pressure is established. This differential is varied within a range and thereafter the evaporative emission space is isolated from communication with the engine and the environment.

US 2005/234631 A1 describes an electronic control device for vehicles, which in addition to a program memory, a computer, wherein a plurality of programs stored in the program memory are connected to a variety of control modes and the computer sequentially executes only programs that are connected to the control mode.

US 2002/083930 A1 shows a device and a method for cleaning a filter for filtering out gases that originate from a tank. It is also provided that when a tank pressure exceeds an adjustable limit, an internal combustion engine is started and the filter is cleaned.

DE 199 13 440 A1 discloses that before opening a fuel cap, an overpressure in a fuel tank can be reduced, for example, via a manually operated switch or via an automatically actuated when opening the fuel filler flap switch, which is in each case connected to eienr control unit.

It is an object of the invention to further develop methods for operating a fuel system of a vehicle.

The object of the invention is achieved by a method for operating a fuel system of a vehicle with electric drive according to claim 1, wherein a pressure within a fuel tank of the fuel system can change situation-related, wherein the pressure within the fuel tank observed and, if necessary, depending on a model-related and / or previously calculated reference pressure is changed.

Since, in particular due to forming fuel vapors often an optionally critical pressure rise within the fuel system can occur, it is particularly advantageous to observe the pressure within the fuel system or the fuel tank, ideally continuously, and if necessary depending on a model-related and / or pre-calculated reference pressure in order to always be able to select the correct situation-related pressure within the fuel system for different operating states.

This is particularly advantageous in vehicles in which the primary drive is realized by an electric motor, which, however, can still carry an internal combustion engine with it.

In particular, the introduction of vehicles with an electric motor for driving the vehicle makes new demands on fuel systems of internal combustion engines, which are carried for example in the form of a range extender with such vehicles in order to expand the range of the vehicle as the emptying of an electric energy storage of the electric drive ,

An observation of the pressure within the fuel system can take place with suitable pressure sensors, for example with an absolute pressure measuring sensor and / or with a differential pressure measuring sensor. Advantageously, such pressure sensors can be dispensed with or their number can be at least reduced if one or more model-related and / or predicted reference pressures could be used, as described by way of example with reference to the following operating states.

With regard to a first operating state, it is provided according to the invention that before a release of a fuel filling device of the fuel system, a closure valve, which is preferably arranged in front of a filter device for fuel gases, opened and the pressure within the fuel tank is changed via the filter device. In this case, the fuel gases, in particular hydrocarbon gases, can be filtered by means of the filter device and thus advantageously do not enter the environment but remain in the fuel system.

An advantageous variant of the method provides in this context that upon reaching a model-related and / or pre-calculated reference pressure, a tank opening of the fuel system is released for opening, whereby a pressure measurement within the fuel system can be dispensed with.

In this respect, it is advantageous if, depending on the model-related and / or predicted reference pressure, the closure valve is opened and the pressure within a fuel tank is changed.

In a second operating state not belonging to the invention, it is advantageous if, depending on the model-related and / or pre-calculated reference pressure, a leakage diagnosis is carried out with respect to the fuel system and the pressure within a fuel tank is changed, whereby it can be constructively easily determined whether fuel gases from the Fuel system may inadvertently enter the environment.

For a pressure modeling in this case, a pressure can be modeled that takes into account pressure changes within the fuel tank due to, for example, the number of gas discharges and their amount or outgassing at the last refueling. In this connection, the measured pressure and the modeled pressure can be compared and it can be determined whether or not there is a leak.

Advantageously, cumulatively or alternatively specifically an overpressure or underpressure can be generated in the fuel tank in order subsequently to be able to carry out an active pressure test.

If no critical pressure change takes place within a certain time interval, a leakage within the fuel system can be excluded.

For example, if a fuel cap of a Kraftstoffeinfülleinrichtung not properly closed, a larger leakage can be detected directly in this case.

It should already be noted at this point that the features relating to the second operating state are also advantageous without the other features of the invention, since these features advantageously further known methods for operating a fuel system.

In a third operating state, it is advantageous if, depending on the model-related saturation of the filter, the fuel system, in particular a filter device of the fuel system, is cleaned of fuel gases, in particular of hydrocarbons.

It is advantageous if, depending on the model-related and / or pre-calculated reference pressure, the filter device of the fuel system with ambient air rinsed and cleaned and the pressure within a fuel tank is changed. By flushing the filter device with ambient air, in particular, an activated carbon filter insert can be regenerated particularly well.

The state of fullness of the activated carbon filter cartridge may be calculated cumulatively or alternatively based on the number of gas discharges and the associated hydrocarbon content modeled.

It should be mentioned here that the features with regard to the third operating state are also advantageous without the other features of the invention, since these features advantageously continue known methods for operating a fuel system.

It is understood that the pressure within the fuel system, in particular within a fuel tank, can be changed in different ways. Often it is already sufficient to open a corresponding valve to effect a pressure change, in particular a pressure reduction.

According to the invention, it is provided that the change in pressure within the fuel system can be carried out by means of commissioning a range extender. In this case, for example, parts of the fuel vapors formed can be burned with the range extender in almost any desired manner. In this respect, the pressure within the fuel system can advantageously be adjusted system-internally by means of the range extender without the need for an immediate pressure equalization with the environment.

Advantageously, a situation-related pressure can also be set by means of the range extender as a function of a model-related and / or predicted reference pressure.

The term "situation-related pressure" in the sense of the invention describes the possibility of being able to change the pressure within the fuel system with regard to certain operating situations in the required manner, this situation-related pressure being set as a function of a model-related and / or predicted reference pressure can be, whereby the pressure can be adapted particularly precisely to the requirements of a particular operating situation, as will be explained below.

The term "range extender" is preferably a specially adapted to a vehicle with electric drive internal combustion engine is described, which does not serve as a prime mover for the present vehicle. Preferably, a generator for generating electrical energy is operated by means of the range extender, in order to either supply a storage device for electrical energy or to supply the electric drive of the present vehicle directly with electrical energy.

The present fuel system may be provided with any suitable components, such as the fuel tank, a fuel filler, filter devices, shut-off valves, and the like. It is understood that the individual components of the present fuel system are fluidly connected to one another by means of a suitable conduit system. The fuel system is designed here in terms of pressure as a closed system.

In this respect, the object of the invention is also a device according to claim 5 for varying a pressure in a fuel system, in particular for carrying out the present method according to one of the explained features, comprising substantially a fuel tank for storing fuel on an electric vehicle, a fuel filler for introducing fuel into the fuel tank and a filter device for filtering fuel gases, the device having a device with means for performing all method steps of the present method according to one of the explained features.

With such a structure, the present device can be made particularly compact and lightweight, so that it can be advantageously used on a large number of electric-powered vehicles.

Advantageously, the device also comprises a device for comparing a current pressure with a model-related and / or pre-calculated reference pressure, which comparison device may be part of the device with means for performing all method steps.

Optionally, the apparatus further includes a pressure sensor for determining a current pressure within the fuel system so that the current pressure within the fuel tank system is always known.

Furthermore, it is advantageous if the device for controlling and / or regulating comprises a vehicle control unit (VCU), a hybrid control unit (HCU) and / or a range extender control unit (RECU). As a result, the present device for controlling and / or regulating can be implemented in a structurally simple manner, it being understood that the device for controlling and / or regulating can advantageously be embodied both as software and as hardware.

If the present device comprises a range extender, with regard to a first method variant with the aid of the range extender an overpressure within the fuel system can be reduced and a tank opening of the fuel system can be released for opening upon reaching a model-related and / or predicted reference pressure. Here, the range extender, for example, just before refueling of fuel put into operation to advantageously reduce excess pressure within the fuel system, so then a fuel cap can be opened. For example, the overpressure is reduced to ambient pressure or slightly above it. This process can be used if, for example, the closure valve can not be opened due to a malfunction.

A release of the tank opening or a relevant fuel filler flap can thus be made structurally particularly simple by means of a differential pressure measurement, in particular by means of a single pressure sensor.

A further method variant not belonging to the invention provides that with the aid of the range extender a negative pressure is generated within the fuel system and a leakage diagnosis with respect to the fuel system can be carried out as a function of a model-related and / or pre-calculated reference pressure. If a corresponding negative pressure within the fuel system is generated by means of the range extender, a leakage diagnosis can be carried out in a manner known per se by measuring the pressure conditions within the fuel system over a suitable period of time.

Preferably, the pressures measured in this case are compared with model-related and / or precalculated reference pressures in order to be able to advantageously obtain indications of a leakage within the fuel system.

It is understood that one or more pressure sensors may be provided at almost any location within the fuel system. Such a pressure sensor is preferably associated with the fuel tank in order to be able to carry out a particularly accurate leak diagnosis in the region of the fuel tank.

Thus, the object of the invention is also achieved by use of a range extender of an electric vehicle for generating a negative pressure in a fuel system of the vehicle with electric drive.

A further variant of the method provides that the fuel system, in particular a filter device of the fuel system, of fuel gases, in particular of hydrocarbons, can be cleaned with the aid of the range extender. For example, in the electric driving mode of the vehicle, the range extender may remain inoperative for a longer period of time, as a result of which fuel vapors arising in the fuel system can not be dissipated by combustion in the internal combustion engine, as is usual in an internal combustion engine-driven motor vehicle. In this respect, there is a risk that in a conventional fuel system, the fuel vapors due to a pressure increase in the environment reach, if the range extender is not used for a long period of electric driving.

In this respect, the object of the invention is also achieved by using a range extender of a vehicle with electric drive for cleaning in particular a fuel filter device of a fuel system of the vehicle with electric drive.

This can advantageously be done modeling the saturation of the fuel gases.

In order to be able to subdivide the fuel system advantageously into suitable regions, in particular with regard to the process variants described above, it is particularly advantageous if in a fuel gas line in front of the filter device, in particular between the filter device and the fuel tank, a fuel gas line shutter valve is disposed.

Cumulatively or alternatively, it is advantageous if in a fuel supply line in front of the range extender, in particular between the range extender and the fuel tank, a fuel supply closing valve is arranged. As a result, further subdivision possibilities can be created.

It is understood that the features of the solutions described above or in the claims can optionally also be combined in order to implement the advantages in a cumulative manner.

Further advantages, objects and features of the present invention will be elucidated with reference to the appended drawing and the description thereof, in which an apparatus and two first method variants for setting a pressure within a fuel system of a vehicle with electric drive are shown and described by way of example.

Figur 1

schematisch eine Vorrichtungsanordnung zum Durchführen der Verfahrensabläufe aus den Figuren 2 und 3;

Figur 2

schematisch ein erstes Flow Chart zu einem nicht beanspruchten Verfahrensablauf einer Leckagediagnose hinsichtlich eines Kraftstoffsystems eines Fahrzeuges mit Elektroantrieb mit einem Range Extender; und

Figur 3

schematisch ein weiteres Flow Chart zu einem beispielhaften Verfahrensablauf einer Freischaltung eines Tankdeckels einer Kraftstoffnachfüllöffnung hinsichtlich eines Kraftstoffsystems eines Fahrzeuges mit Elektroantrieb mit einem Range Extender.

Show it:

FIG. 1

schematically a device arrangement for performing the procedures of the Figures 2 and 3 ;

FIG. 2

schematically a first flow chart for a non-claimed process sequence of a leak diagnosis with respect to a fuel system of an electric vehicle with a range extender; and

FIG. 3

schematically another flow chart for an exemplary process flow of activation of a fuel cap of a Kraftstoffnachfüllöffnung with respect to a fuel system of a vehicle with electric drive with a range extender.

The in the FIG. 1 1 for setting a pressure 2 in a fuel system 3 comprises a range extender 4 with an engine control unit 5 (ECU) in the form of an internal combustion engine 6 with a generator 7 for generating electric power Energy for a prime mover of an electric drive not shown here of a vehicle also not shown here.

In addition, the device 1 comprises a fuel tank 8 for storing fuel 9, a fuel filling device 10 with a mechanically and / or electrically lockable tank lid 11, a filter device 12 for filtering fuel gases 13 with an activated carbon filter insert 14.

The range extender 4 is fluidly connected to the fuel tank 8 on the one hand via a fuel supply line 15 and on the other hand via a fuel gas supply line 16. In the fuel gas supply line 16 is located on the range extender 4, a fuel supply closing valve 17, by means of which the range extender 4 can be fluidly separated from fuel gas supply line 16 if necessary. This is particularly advantageous if, in particular, the methods or method variants described above are to be carried out without intervention of the range extender 4.

The fuel gas supply line 16 is flanged to a fuel gas discharge line 18, which leads from the fuel tank 8 to the filter device 12.

In front of the filter device 12, that is to say between the fuel tank 8 and the filter device 12, a fuel gas line closure valve 19 is advantageously arranged so that the filter device 12 can be fluidically separated from the fuel gas discharge line 18. This is particularly advantageous if, for example, in the fuel tank 8, possibly adjusted by means of the range extender 4, a certain pressure and pressure equalization with the atmosphere via the filter device 12 should be avoided.

On the fuel tank 8, a level sensor 20 and the other a pressure sensor 21 are provided on the one hand, by means of the pressure sensor 21 generally a pressure 2 measured within the fuel system 3 and can be indicated for example at an evaluation device 22.

In addition, the device 1 has a device 23 for controlling and / or regulating, by means of which additionally the currently measured pressure 2 with a model-related and / or predicted reference pressure can be compared, by means of which in particular the operation of the range extender 4 can be coordinated.

But also a control of the valves 17 and 19 and the control of the tank lid 11 can be taken over by the device 23. For this purpose, the device 23 is connected via corresponding data lines 24 (here explicitly numbered between the engine control unit 5 and the device 23) to the individual components.

The device 23 can be realized, for example, by means of a vehicle control unit (VCU), a range extender control unit (RECU) and / or a hybrid control unit (HCU), as indicated in this exemplary embodiment.

That in the FIG. 2 The first flow chart 30 shown by way of example and not claimed starts with a tank diagnostic request 31, as a result of which an operation query 32 regarding the range extender 4 is made.

If the operating query 32 is affirmative, ie, the operation of the range extender 4 is confirmed, a negative pressure is generated in a following step 33 and tested according to a comparison query 34, if the current pressure 2 coincides with a model-related and / or pre-calculated reference pressure.

In another test query 35 is checked whether there is a critical pressure deviation in this regard. If such a critical pressure deviation is determined, a leakage warning 36 is output. Otherwise, a normal function 37 is confirmed.

If the operation query 32 described above is denied, a test routine 38 takes place, by means of which an overpressure is to be determined and confirmed specifically in the fuel tank 8.

If such a confirmation, is continued with the process sequence 34 described above.

If, however, the operation query 32 is answered in the negative, an emergency diagnosis 39 is carried out, in particular for compliance with specific regulations in an alternative subsequent step.

If the urgency diagnosis 39 remains negative, in a next step 40, the system waits until the pressure 2 within the fuel system 3 rises. Subsequently, the operation query 32 again.

If the urgency diagnosis 39 is positive, the range extender 4 is started in an alternative step 41. Subsequently, the operation query 32 again.

That in the FIG. 3 explained further flow chart 50 starts with a tank activity 51, in consequence of which an overpressure diagnosis 52 is made with respect to the fuel tank 8.

If there is no overpressure 2, an evaporation valve 19 is then activated in a next method step 53, and in a subsequent step 54, a tank lid closure of the tank lid 11 is released.

During the actual refueling process, in a further step 55, fuel gases 13 are filtered through the filter device 12 and released into the atmosphere.

Subsequently, a saturation diagnosis 56 is made with regard to the activated carbon filter 14 of the filter device 12.

If an overpressure is detected with regard to the above-mentioned overpressure diagnosis 52, an evaporation valve 19 is subsequently also activated in the next method step 53, and in a subsequent step 57 the fuel gases 13 are filtered through the filter device 12 and released into the atmosphere. Subsequently, the previously described steps 54, 55 and 56 can be initiated or made.

At the same time, saturation of the activated carbon filter insert 14 in dependence on a current tank pressure 2, a current fill level of the fuel tank 8, a current temperature, etc. is determined in a parallel step 58.

This results in a rating query 59, whether the activated carbon filter cartridge 14 has reached a critical saturation or not.

If there is a critical saturation, a notification request 60 regarding a range extender operation and an activated charcoal filter cleaner is sent to the engine control unit 5 at a next vehicle use.

If there is no critical saturation, an alternative notification request 61 regarding activated charcoal filter cleaning is sent to the engine control unit 5 during a next range extender operation.

All disclosed in the application documents features are claimed as essential to the invention, provided they are new individually or in combination over the prior art.

LIST OF REFERENCE NUMBERS

1

contraption

2

print

3

Fuel system

4

Range extender

5

Engine control unit

6

Internal combustion engine

7

generator

8th

Fuel tank

9

fuel

10

Kraftstoffeinfülleinrichtung

11

filler cap

12

filtering device

13

Fuel gases

14

Activated carbon filter cartridge

15

Fuel supply

16

Fuel gas supply line

17

Fuel feedline closure valve

18

Fuel gas discharge

19

Fuel gas derivative closure valve

20

level sensor

21

pressure sensor

22

evaluation

23

Device for controlling and / or regulating

24

data lines

30

first flow chart

31

Tank diagnostic request

32

operating query

33

following step

34

Compare query

35

Prompted Test

36

leakage warning

37

normal function

38

check routine

39

emergency diagnosis

40

Next Step

41

alternative step

50

another flow chart

51

tank activity

52

Overpressure diagnosis

53

next process step

54

following step

55

another step

56

saturation diagnosis

57

following step

58

parallel step

59

review query

60

notification request

61

alternative notification request

Claims (6)

1. Method for operating a fuel system (3) of a vehicle having an electric drive system, in which a pressure (2) inside a fuel tank (8) of the fuel system (3) can modify depending on the situation, the pressure (2) inside the fuel tank (8) being monitored and, where required, modified on the basis of a model-specific and/or precalculated reference pressure, the pressure (2) inside the fuel system (3) being modified by putting into operation a range extender (4) or a fuel gas line shut-off valve (19), characterised in that
   the shut-off valve is opened before a release of a fuel filling device (10) of the fuel system (3), and the pressure (2) inside the fuel tank (8) is modified by means of a filter device (12) and, at the same time, a saturation of the activated carbon filter insert (14) of the filter device (12) being determined on the basis of a present tank pressure (2), and, when the saturation is critical, a notification request (60) concerning a range extender operation and an activated carbon filter insert cleaning process being sent to an engine control unit (5) upon subsequent use of the vehicle, the shut-off valve (19) preferably being arranged upstream of the filter device (12).
2. Method according to claim 1,
   characterised in that,
   on the basis of the model-specific and/or precalculated reference pressure, the shut-off valve (19) is opened and the pressure (2) inside a fuel tank (8) is modified.
3. Method according to either claim 1 or claim 2,
   characterised in that,
   on the basis of the model-specific and/or precalculated reference pressure, the fuel system (3), in particular a filter device (12) of the fuel system (3), is cleaned to remove fuel gases (13), in particular hydrocarbons, and the pressure (2) inside a fuel tank (8) is modified.
4. Method according to claim 3,
   characterised in that,
   on the basis of the model-specific and/or precalculated reference pressure, the filter device (12) of the fuel system (3) is flushed and cleaned with ambient air and the pressure (2) inside a fuel tank (8) is modified.
5. Device (1) for modifying a pressure (2) in a fuel system (3), in particular for carrying out the method according to any of the preceding claims, substantially comprising a fuel tank (8) for supplying fuel (9) to a vehicle having an electric drive system, a fuel filling device (10) for filling fuel (9) into the fuel tank (8), a filter device (12) for filtering fuel gases (13) comprising an activated carbon filter insert (14), the device comprising a range extender (4) or a fuel gas line shut-off valve (19) for modifying the pressure (2) inside the fuel system,
   characterised by
   a device (23) comprising means for carrying out all the method steps according to any of the preceding claims, a shut-off valve (19), which is preferably arranged upstream of the filter device (12) for fuel gases, being opened before a release of a fuel filling device (10) of the fuel system (3), and the pressure (2) inside the fuel tank (8) being modified by means of the filter device (12) and, at the same time, a saturation of the activated carbon filter insert (14) being determined on the basis of a present tank pressure (2), and, when a saturation is critical, a notification request (60) concerning a range extender operation and an activated carbon filter insert cleaning process being sent to an engine control unit (5) upon subsequent use of the vehicle.
6. Device (1) according to claim 5,
   characterised in that
   the open-loop and/or closed-loop control device (23) comprises a vehicle control unit (VCU), a hybrid control unit (HCU) and/or a range extender control unit (RECU).

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