DE102009057227A1 - A method of operating a fuel system and apparatus for varying a pressure in a fuel system - Google Patents

Abstract

To further develop known fuel system operating methods of a vehicle, the invention proposes a method for operating a fuel system of an electric vehicle in which a pressure within a fuel tank of the fuel system may vary according to the situation, wherein the method is characterized in that the pressure within the fuel tank observed and changed as needed in response to a model-related and / or pre-calculated reference pressure.

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.

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, in which a pressure within a fuel tank of the fuel system may vary according to the situation, wherein the method is characterized in that the pressure within the fuel tank observed and when needed in Dependence of a model-related and / or pre-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 advantageous if, prior to 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, is 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, it is advantageous if, depending on the model-related and / or pre-calculated reference pressure, a leakage diagnosis with respect to the Fuel system performed and the pressure is changed within a fuel tank, which can be structurally easily determined whether fuel gases from the fuel system can inadvertently get into 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.

In this case, it is advantageous if, depending on the model-related and / or previously calculated reference pressure, the filter device of the fuel system is purged and cleaned with ambient air 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.

Cumulatively or alternatively, it is advantageous if the change in pressure within the fuel system is 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 context of the invention describes the possibility of being able to change the pressure within the fuel system as required with respect to certain operating situations, whereby this situation-related pressure can be set as a function of a model-related and / or predicted reference pressure, whereby the pressure can be particularly precisely adapted 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 each other 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 for changing 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 filling device for filling Dissolved fuel in the fuel tank and a filter device for filtering fuel gases, the device being a device for controlling and / or regulating 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, wherein this comparison device may be part of the device for controlling and / or regulating.

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.

Thus, the object of the invention is also achieved by using a range extender of an electric vehicle to reduce overpressure in a fuel system of the electric vehicle.

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 variant of the method provides that a vacuum is generated within the fuel system with the aid of the range extender and a leakage diagnosis with respect to the fuel system can be carried out as a function of a model-related and / or predicted 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 drive mode of the vehicle, the range extender may remain inoperative for a longer period of time, whereby fuel vapors arising in the fuel system can not be reduced by combustion in the internal combustion engine, as is customary in a motor vehicle operated by an internal combustion engine. 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, particularly with regard to the process variants described above, it is particularly favorable if a fuel gas line closure valve is arranged in a fuel gas line upstream of the filter device, in particular between the filter device and the fuel tank.

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.

Show it:

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

2 schematically a first flow chart for an exemplary procedure of a leak diagnosis with respect to a fuel system of an electric vehicle with a range extender; and

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 1 shown device 1 to set a pressure 2 in a fuel system 3 includes 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 electrical energy for a prime mover of an electric drive not shown here of a vehicle also not shown here.

In addition, the device includes 1 a fuel tank 8th for storing fuel 9 , a fuel filler 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 element 14 ,

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

The fuel gas supply line 16 is due to a fuel gas discharge 18 Flanged, which of the fuel tank 8th to the filter device 12 leads.

In front of the filter device 12 So, between the fuel tank 8th and the filter device 12 , Advantageously, a fuel gas line closing valve 19 arranged so that the filter device 12 fluidic of the fuel gas discharge 18 can be separated. This is particularly advantageous if, for example, in the fuel tank 8th , if necessary by means of the range extender 4 , set a certain pressure and pressure equalization with the atmosphere through the filter device 12 should be avoided.

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

In addition, the device has 1 about a device 23 for controlling and / or regulating, by means of which in addition also the currently measured pressure 2 can be compared with a model-related and / or pre-calculated reference pressure, 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 as well as the control of the gas cap 11 can from the decor 23 be taken over. This is the device 23 via appropriate data lines 24 (here explicitly between the engine control unit 5 and the facility 23 numbered) connected to the individual components.

The device 23 can for example be realized 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 embodiment.

That in the 2 exemplified first flow chart 30 starts with a tank diagnostic request 31 , as a result of which an operation inquiry 32 in terms of range extender 4 is made.

Will the operation query 32 yes, so the operation of the range extender 4 confirmed, will be in a subsequent step 33 generates a negative pressure and according to a comparison query 34 checked if the current pressure 2 coincides with a model-related and / or pre-calculated reference pressure.

For another check request 35 It is checked whether there is a critical pressure deviation in this regard. If such a critical pressure deviation is determined, a leakage warning will be issued 36 output. Otherwise it becomes a normal function 37 approved.

Will the operation query described above 32 denies a check routine 38 , by means of which an overpressure especially in the fuel tank 8th determined and confirmed.

If such an acknowledgment, is with the process sequence described above 34 continued.

Will the operation query 32 however, in the negative, an urgency diagnosis is made, in particular, in order to comply with specific rules in an alternative subsequent step 39 carried out.

Remains the urgency diagnosis 39 negative, will be in a next step 40 Wait until the pressure 2 within the fuel system 3 increases. Subsequently, the operation query takes place again 32 ,

If the urgency diagnosis fails 39 Positive, the range extender 4 in an alternative step 41 started. Subsequently, the operation query takes place again 32 ,

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

There is no overpressure 2 before, is then in a next step 53 an evaporation valve 19 activated and in a subsequent step 54 becomes a gas cap lid of the gas cap 11 Approved.

During the actual refueling process, in a further step 55 Fuel gases 13 over the filter device 12 filtered to release the atmosphere.

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

With regard to the above-mentioned overpressure diagnosis 52 a positive pressure is detected, then also in the next step 53 an evaporation valve 19 activated and in a subsequent step 57 become the fuel gases 13 over the filter device 12 filtered to release the atmosphere. You can then follow the steps previously described 54 . 55 and 56 initiated or made.

At the same time, in a parallel step 58 a saturation of the activated carbon filter cartridge 14 depending on a current tank pressure 2 , a current level of the fuel tank 8th , a current temperature and so on.

This results in a valuation 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 becomes 60 for a range extender operation and an activated charcoal filter cleaning on the next vehicle use to the engine control unit 5 Posted.

If there is no critical saturation, then an alternate notification request will be made 61 regarding activated charcoal filter cleaning during a next range extender operation to the engine control unit 5 Posted.

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

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006034076 A1 [0003]

Claims (10)

Method for operating a fuel system ( 3 ) of a vehicle with electric drive, in which a pressure ( 2 ) within a fuel tank ( 8th ) of the fuel system ( 3 ) can change situation-dependent, characterized in that the pressure ( 2 ) inside the fuel tank ( 8th ) and, if necessary, changed as a function of a model-related and / or pre-calculated reference pressure. A method according to claim 1, characterized in that prior to release of a Kraftstoffeinfülleinrichtung ( 10 ) of the fuel system ( 3 ) a closure valve ( 19 ), which preferably before a filter device ( 12 ) is arranged for fuel gases, opened and the pressure ( 2 ) inside the fuel tank ( 8th ) via the filter device ( 12 ) is changed. A method according to claim 2, characterized in that depending on the model-related and / or pre-calculated reference pressure, the closure valve ( 19 ) and the pressure ( 2 ) within a fuel tank ( 8th ) is changed. A method according to claim 1, characterized in that depending on the model-related and / or pre-calculated reference pressure, a leakage diagnosis with respect to the fuel system ( 3 ) and the pressure ( 2 ) within a fuel tank ( 8th ) is changed. A method according to claim 1, characterized in that depending on the model-related and / or pre-calculated reference pressure, the fuel system ( 3 ), in particular a filter device ( 12 ) of the fuel system ( 3 ), of fuel gases ( 13 ), in particular of hydrocarbons, and the pressure ( 2 ) within a fuel tank ( 8th ) is changed. A method according to claim 5, characterized in that depending on the model-related and / or pre-calculated reference pressure, the filter device ( 12 ) of the fuel system ( 3 ) is purged and cleaned with ambient air and the pressure ( 2 ) within a fuel tank ( 8th ) is changed. Method according to one of claims 1 to 6, characterized in that the change in pressure ( 2 ) within the fuel system ( 3 ) by commissioning a range extender ( 4 ) is carried out. Contraption ( 1 ) for changing a pressure ( 2 ) in a fuel system ( 3 ), in particular for carrying out the method according to one of the preceding claims, comprising essentially a fuel tank ( 8th ) for storing fuel ( 9 ) on an electric vehicle, a fuel filler ( 10 ) for filling fuel ( 9 ) in the fuel tank ( 8th ) and a filter device ( 12 ) for filtering fuel gases ( 13 ), characterized in that the device ( 1 ) An institution ( 23 ) for controlling and / or regulating a method according to any one of the preceding claims. Contraption ( 1 ) according to claim 8, characterized in that the device ( 23 ) comprises a vehicle control unit (VCU), a hybrid control unit (HCU) and / or a range extender control unit (RECU) for controlling and / or regulating. Contraption ( 1 ) according to claim 8 or 9, characterized in that in a fuel gas line ( 18 ) in front of the filter device ( 12 ), in particular between the filter device ( 12 ) and the fuel tank ( 8th ), a fuel gas line closing valve ( 19 ) is arranged.

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